diff --git a/ChangeLog.d/add-missing-parenthesis.txt b/ChangeLog.d/add-missing-parenthesis.txt
new file mode 100644
index 0000000..9576ff3
--- /dev/null
+++ b/ChangeLog.d/add-missing-parenthesis.txt
@@ -0,0 +1,3 @@
+Bugfix
+   * Fix a compilation error when MBEDTLS_ECP_RANDOMIZE_MXZ_ALT is
+     defined. Fixes #4217.
diff --git a/ChangeLog.d/fix-pk-parse-key-error-code.txt b/ChangeLog.d/fix-pk-parse-key-error-code.txt
new file mode 100644
index 0000000..3aa330b
--- /dev/null
+++ b/ChangeLog.d/fix-pk-parse-key-error-code.txt
@@ -0,0 +1,2 @@
+Bugfix
+   * Fix an incorrect error code when parsing a PKCS#8 private key.
diff --git a/ChangeLog.d/psa-aead-output-size-macros-1.0.txt b/ChangeLog.d/psa-aead-output-size-macros-1.0.txt
new file mode 100644
index 0000000..22756f1
--- /dev/null
+++ b/ChangeLog.d/psa-aead-output-size-macros-1.0.txt
@@ -0,0 +1,5 @@
+API changes
+   * Update AEAD output size macros to bring them in line with the PSA Crypto
+     API version 1.0 spec. This version of the spec parameterizes them on the
+     key type used, as well as the key bit-size in the case of
+     PSA_AEAD_TAG_LENGTH.
diff --git a/include/mbedtls/error.h b/include/mbedtls/error.h
index 0ea1d06..7936f6b 100644
--- a/include/mbedtls/error.h
+++ b/include/mbedtls/error.h
@@ -30,6 +30,11 @@
 
 #include <stddef.h>
 
+#if ( defined(__ARMCC_VERSION) || defined(_MSC_VER) ) && \
+    !defined(inline) && !defined(__cplusplus)
+#define inline __inline
+#endif
+
 /**
  * Error code layout.
  *
@@ -118,6 +123,54 @@
 #define MBEDTLS_ERR_PLATFORM_FEATURE_UNSUPPORTED -0x0072 /**< The requested feature is not supported by the platform */
 
 /**
+ * \brief Combines a high-level and low-level error code together.
+ *
+ *        Wrapper macro for mbedtls_error_add(). See that function for
+ *        more details.
+ */
+#define MBEDTLS_ERROR_ADD( high, low ) \
+        mbedtls_error_add( high, low, __FILE__, __LINE__ )
+
+#if defined(MBEDTLS_TEST_HOOKS)
+/**
+ * \brief Testing hook called before adding/combining two error codes together.
+ *        Only used when invasive testing is enabled via MBEDTLS_TEST_HOOKS.
+ */
+extern void (*mbedtls_test_hook_error_add)( int, int, const char *, int );
+#endif
+
+/**
+ * \brief Combines a high-level and low-level error code together.
+ *
+ *        This function can be called directly however it is usually
+ *        called via the #MBEDTLS_ERROR_ADD macro.
+ *
+ *        While a value of zero is not a negative error code, it is still an
+ *        error code (that denotes success) and can be combined with both a
+ *        negative error code or another value of zero.
+ *
+ * \note  When invasive testing is enabled via #MBEDTLS_TEST_HOOKS, also try to
+ *        call \link mbedtls_test_hook_error_add \endlink.
+ *
+ * \param high      high-level error code. See error.h for more details.
+ * \param low       low-level error code. See error.h for more details.
+ * \param file      file where this error code addition occured.
+ * \param line      line where this error code addition occured.
+ */
+static inline int mbedtls_error_add( int high, int low,
+                                     const char *file, int line )
+{
+#if defined(MBEDTLS_TEST_HOOKS)
+    if( *mbedtls_test_hook_error_add != NULL )
+        ( *mbedtls_test_hook_error_add )( high, low, file, line );
+#endif
+    (void)file;
+    (void)line;
+
+    return( high + low );
+}
+
+/**
  * \brief Translate a mbed TLS error code into a string representation,
  *        Result is truncated if necessary and always includes a terminating
  *        null byte.
diff --git a/include/psa/crypto.h b/include/psa/crypto.h
index 81e1f28..94b8f99 100644
--- a/include/psa/crypto.h
+++ b/include/psa/crypto.h
@@ -2113,9 +2113,16 @@
  *                                authentication tag is appended to the
  *                                encrypted data.
  * \param ciphertext_size         Size of the \p ciphertext buffer in bytes.
- *                                This must be at least
- *                                #PSA_AEAD_ENCRYPT_OUTPUT_SIZE(\p alg,
- *                                \p plaintext_length).
+ *                                This must be appropriate for the selected
+ *                                algorithm and key:
+ *                                - A sufficient output size is
+ *                                  #PSA_AEAD_ENCRYPT_OUTPUT_SIZE(\c key_type,
+ *                                  \p alg, \p plaintext_length) where
+ *                                  \c key_type is the type of \p key.
+ *                                - #PSA_AEAD_ENCRYPT_OUTPUT_MAX_SIZE(\p
+ *                                  plaintext_length) evaluates to the maximum
+ *                                  ciphertext size of any supported AEAD
+ *                                  encryption.
  * \param[out] ciphertext_length  On success, the size of the output
  *                                in the \p ciphertext buffer.
  *
@@ -2129,7 +2136,11 @@
  *         \p alg is not supported or is not an AEAD algorithm.
  * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
  * \retval #PSA_ERROR_BUFFER_TOO_SMALL
- *         \p ciphertext_size is too small
+ *         \p ciphertext_size is too small.
+ *         #PSA_AEAD_ENCRYPT_OUTPUT_SIZE(\c key_type, \p alg,
+ *         \p plaintext_length) or
+ *         #PSA_AEAD_ENCRYPT_OUTPUT_MAX_SIZE(\p plaintext_length) can be used to
+ *         determine the required buffer size.
  * \retval #PSA_ERROR_COMMUNICATION_FAILURE
  * \retval #PSA_ERROR_HARDWARE_FAILURE
  * \retval #PSA_ERROR_CORRUPTION_DETECTED
@@ -2173,9 +2184,16 @@
  * \param ciphertext_length       Size of \p ciphertext in bytes.
  * \param[out] plaintext          Output buffer for the decrypted data.
  * \param plaintext_size          Size of the \p plaintext buffer in bytes.
- *                                This must be at least
- *                                #PSA_AEAD_DECRYPT_OUTPUT_SIZE(\p alg,
- *                                \p ciphertext_length).
+ *                                This must be appropriate for the selected
+ *                                algorithm and key:
+ *                                - A sufficient output size is
+ *                                  #PSA_AEAD_DECRYPT_OUTPUT_SIZE(\c key_type,
+ *                                  \p alg, \p ciphertext_length) where
+ *                                  \c key_type is the type of \p key.
+ *                                - #PSA_AEAD_DECRYPT_OUTPUT_MAX_SIZE(\p
+ *                                  ciphertext_length) evaluates to the maximum
+ *                                  plaintext size of any supported AEAD
+ *                                  decryption.
  * \param[out] plaintext_length   On success, the size of the output
  *                                in the \p plaintext buffer.
  *
@@ -2191,7 +2209,11 @@
  *         \p alg is not supported or is not an AEAD algorithm.
  * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
  * \retval #PSA_ERROR_BUFFER_TOO_SMALL
- *         \p plaintext_size or \p nonce_length is too small
+ *         \p plaintext_size is too small.
+ *         #PSA_AEAD_DECRYPT_OUTPUT_SIZE(\c key_type, \p alg,
+ *         \p ciphertext_length) or
+ *         #PSA_AEAD_DECRYPT_OUTPUT_MAX_SIZE(\p ciphertext_length) can be used
+ *         to determine the required buffer size.
  * \retval #PSA_ERROR_COMMUNICATION_FAILURE
  * \retval #PSA_ERROR_HARDWARE_FAILURE
  * \retval #PSA_ERROR_CORRUPTION_DETECTED
@@ -2612,10 +2634,18 @@
  * \param input_length          Size of the \p input buffer in bytes.
  * \param[out] output           Buffer where the output is to be written.
  * \param output_size           Size of the \p output buffer in bytes.
- *                              This must be at least
- *                              #PSA_AEAD_UPDATE_OUTPUT_SIZE(\c alg,
- *                              \p input_length) where \c alg is the
- *                              algorithm that is being calculated.
+ *                              This must be appropriate for the selected
+ *                                algorithm and key:
+ *                                - A sufficient output size is
+ *                                  #PSA_AEAD_UPDATE_OUTPUT_SIZE(\c key_type,
+ *                                  \c alg, \p input_length) where
+ *                                  \c key_type is the type of key and \c alg is
+ *                                  the algorithm that were used to set up the
+ *                                  operation.
+ *                                - #PSA_AEAD_UPDATE_OUTPUT_MAX_SIZE(\p
+ *                                  input_length) evaluates to the maximum
+ *                                  output size of any supported AEAD
+ *                                  algorithm.
  * \param[out] output_length    On success, the number of bytes
  *                              that make up the returned output.
  *
@@ -2626,9 +2656,9 @@
  *         set, and have lengths set if required by the algorithm).
  * \retval #PSA_ERROR_BUFFER_TOO_SMALL
  *         The size of the \p output buffer is too small.
- *         You can determine a sufficient buffer size by calling
- *         #PSA_AEAD_UPDATE_OUTPUT_SIZE(\c alg, \p input_length)
- *         where \c alg is the algorithm that is being calculated.
+ *         #PSA_AEAD_UPDATE_OUTPUT_SIZE(\c key_type, \c alg, \p input_length) or
+ *         #PSA_AEAD_UPDATE_OUTPUT_MAX_SIZE(\p input_length) can be used to
+ *         determine the required buffer size.
  * \retval #PSA_ERROR_INVALID_ARGUMENT
  *         The total length of input to psa_aead_update_ad() so far is
  *         less than the additional data length that was previously
@@ -2665,9 +2695,7 @@
  * This function has two output buffers:
  * - \p ciphertext contains trailing ciphertext that was buffered from
  *   preceding calls to psa_aead_update().
- * - \p tag contains the authentication tag. Its length is always
- *   #PSA_AEAD_TAG_LENGTH(\c alg) where \c alg is the AEAD algorithm
- *   that the operation performs.
+ * - \p tag contains the authentication tag.
  *
  * When this function returns successfuly, the operation becomes inactive.
  * If this function returns an error status, the operation enters an error
@@ -2677,18 +2705,32 @@
  * \param[out] ciphertext       Buffer where the last part of the ciphertext
  *                              is to be written.
  * \param ciphertext_size       Size of the \p ciphertext buffer in bytes.
- *                              This must be at least
- *                              #PSA_AEAD_FINISH_OUTPUT_SIZE(\c alg) where
- *                              \c alg is the algorithm that is being
- *                              calculated.
+ *                              This must be appropriate for the selected
+ *                              algorithm and key:
+ *                              - A sufficient output size is
+ *                                #PSA_AEAD_FINISH_OUTPUT_SIZE(\c key_type,
+ *                                \c alg) where \c key_type is the type of key
+ *                                and \c alg is the algorithm that were used to
+ *                                set up the operation.
+ *                              - #PSA_AEAD_FINISH_OUTPUT_MAX_SIZE evaluates to
+ *                                the maximum output size of any supported AEAD
+ *                                algorithm.
  * \param[out] ciphertext_length On success, the number of bytes of
  *                              returned ciphertext.
  * \param[out] tag              Buffer where the authentication tag is
  *                              to be written.
  * \param tag_size              Size of the \p tag buffer in bytes.
- *                              This must be at least
- *                              #PSA_AEAD_TAG_LENGTH(\c alg) where \c alg is
- *                              the algorithm that is being calculated.
+ *                              This must be appropriate for the selected
+ *                              algorithm and key:
+ *                              - The exact tag size is #PSA_AEAD_TAG_LENGTH(\c
+ *                                key_type, \c key_bits, \c alg) where
+ *                                \c key_type and \c key_bits are the type and
+ *                                bit-size of the key, and \c alg is the
+ *                                algorithm that were used in the call to
+ *                                psa_aead_encrypt_setup().
+ *                              - #PSA_AEAD_TAG_MAX_SIZE evaluates to the
+ *                                maximum tag size of any supported AEAD
+ *                                algorithm.
  * \param[out] tag_length       On success, the number of bytes
  *                              that make up the returned tag.
  *
@@ -2699,11 +2741,11 @@
  *         operation with a nonce set).
  * \retval #PSA_ERROR_BUFFER_TOO_SMALL
  *         The size of the \p ciphertext or \p tag buffer is too small.
- *         You can determine a sufficient buffer size for \p ciphertext by
- *         calling #PSA_AEAD_FINISH_OUTPUT_SIZE(\c alg)
- *         where \c alg is the algorithm that is being calculated.
- *         You can determine a sufficient buffer size for \p tag by
- *         calling #PSA_AEAD_TAG_LENGTH(\c alg).
+ *         #PSA_AEAD_FINISH_OUTPUT_SIZE(\c key_type, \c alg) or
+ *         #PSA_AEAD_FINISH_OUTPUT_MAX_SIZE can be used to determine the
+ *         required \p ciphertext buffer size. #PSA_AEAD_TAG_LENGTH(\c key_type,
+ *         \c key_bits, \c alg) or #PSA_AEAD_TAG_MAX_SIZE can be used to
+ *         determine the required \p tag buffer size.
  * \retval #PSA_ERROR_INVALID_ARGUMENT
  *         The total length of input to psa_aead_update_ad() so far is
  *         less than the additional data length that was previously
@@ -2762,10 +2804,15 @@
  *                              that could not be processed until the end
  *                              of the input.
  * \param plaintext_size        Size of the \p plaintext buffer in bytes.
- *                              This must be at least
- *                              #PSA_AEAD_VERIFY_OUTPUT_SIZE(\c alg) where
- *                              \c alg is the algorithm that is being
- *                              calculated.
+ *                              This must be appropriate for the selected algorithm and key:
+ *                              - A sufficient output size is
+ *                                #PSA_AEAD_VERIFY_OUTPUT_SIZE(\c key_type,
+ *                                \c alg) where \c key_type is the type of key
+ *                                and \c alg is the algorithm that were used to
+ *                                set up the operation.
+ *                              - #PSA_AEAD_VERIFY_OUTPUT_MAX_SIZE evaluates to
+ *                                the maximum output size of any supported AEAD
+ *                                algorithm.
  * \param[out] plaintext_length On success, the number of bytes of
  *                              returned plaintext.
  * \param[in] tag               Buffer containing the authentication tag.
@@ -2781,9 +2828,9 @@
  *         operation with a nonce set).
  * \retval #PSA_ERROR_BUFFER_TOO_SMALL
  *         The size of the \p plaintext buffer is too small.
- *         You can determine a sufficient buffer size for \p plaintext by
- *         calling #PSA_AEAD_VERIFY_OUTPUT_SIZE(\c alg)
- *         where \c alg is the algorithm that is being calculated.
+ *         #PSA_AEAD_VERIFY_OUTPUT_SIZE(\c key_type, \c alg) or
+ *         #PSA_AEAD_VERIFY_OUTPUT_MAX_SIZE can be used to determine the
+ *         required buffer size.
  * \retval #PSA_ERROR_INVALID_ARGUMENT
  *         The total length of input to psa_aead_update_ad() so far is
  *         less than the additional data length that was previously
diff --git a/include/psa/crypto_sizes.h b/include/psa/crypto_sizes.h
index c9de062..79f9673 100644
--- a/include/psa/crypto_sizes.h
+++ b/include/psa/crypto_sizes.h
@@ -117,26 +117,35 @@
  */
 #define PSA_MAC_MAX_SIZE PSA_HASH_MAX_SIZE
 
-/** The tag size for an AEAD algorithm, in bytes.
+/** The length of a tag for an AEAD algorithm, in bytes.
  *
+ * This macro can be used to allocate a buffer of sufficient size to store the
+ * tag output from psa_aead_finish().
+ *
+ * See also #PSA_AEAD_TAG_MAX_SIZE.
+ *
+ * \param key_type            The type of the AEAD key.
+ * \param key_bits            The size of the AEAD key in bits.
  * \param alg                 An AEAD algorithm
  *                            (\c PSA_ALG_XXX value such that
  *                            #PSA_ALG_IS_AEAD(\p alg) is true).
  *
- * \return                    The tag size for the specified algorithm.
+ * \return                    The tag length for the specified algorithm and key.
  *                            If the AEAD algorithm does not have an identified
  *                            tag that can be distinguished from the rest of
  *                            the ciphertext, return 0.
- *                            If the AEAD algorithm is not recognized, return 0.
+ *                            If the key type or AEAD algorithm is not
+ *                            recognized, or the parameters are incompatible,
+ *                            return 0.
  */
-#define PSA_AEAD_TAG_LENGTH(alg)                                        \
-    (PSA_ALG_IS_AEAD(alg) ?                                             \
-     (((alg) & PSA_ALG_AEAD_TAG_LENGTH_MASK) >> PSA_AEAD_TAG_LENGTH_OFFSET) : \
-     0)
+#define PSA_AEAD_TAG_LENGTH(key_type, key_bits, alg)                        \
+    (PSA_AEAD_NONCE_LENGTH(key_type, alg) != 0 ?                            \
+     PSA_ALG_AEAD_GET_TAG_LENGTH(alg) :                                     \
+     ((void) (key_bits), 0))
 
 /** The maximum tag size for all supported AEAD algorithms, in bytes.
  *
- * See also #PSA_AEAD_TAG_LENGTH(\p alg).
+ * See also #PSA_AEAD_TAG_LENGTH(\p key_type, \p key_bits, \p alg).
  */
 #define PSA_AEAD_TAG_MAX_SIZE       16
 
@@ -241,10 +250,14 @@
  * insufficient buffer size. Depending on the algorithm, the actual size of
  * the ciphertext may be smaller.
  *
+ * See also #PSA_AEAD_ENCRYPT_OUTPUT_MAX_SIZE(\p plaintext_length).
+ *
  * \warning This macro may evaluate its arguments multiple times or
  *          zero times, so you should not pass arguments that contain
  *          side effects.
  *
+ * \param key_type            A symmetric key type that is
+ *                            compatible with algorithm \p alg.
  * \param alg                 An AEAD algorithm
  *                            (\c PSA_ALG_XXX value such that
  *                            #PSA_ALG_IS_AEAD(\p alg) is true).
@@ -252,11 +265,13 @@
  *
  * \return                    The AEAD ciphertext size for the specified
  *                            algorithm.
- *                            If the AEAD algorithm is not recognized, return 0.
+ *                            If the key type or AEAD algorithm is not
+ *                            recognized, or the parameters are incompatible,
+ *                            return 0.
  */
-#define PSA_AEAD_ENCRYPT_OUTPUT_SIZE(alg, plaintext_length)       \
-    (PSA_AEAD_TAG_LENGTH(alg) != 0 ?                              \
-     (plaintext_length) + PSA_AEAD_TAG_LENGTH(alg) :              \
+#define PSA_AEAD_ENCRYPT_OUTPUT_SIZE(key_type, alg, plaintext_length) \
+    (PSA_AEAD_NONCE_LENGTH(key_type, alg) != 0 ?                      \
+     (plaintext_length) + PSA_ALG_AEAD_GET_TAG_LENGTH(alg) :          \
      0)
 
 /** A sufficient output buffer size for psa_aead_encrypt(), for any of the
@@ -268,7 +283,8 @@
  * \note This macro returns a compile-time constant if its arguments are
  *       compile-time constants.
  *
- * See also #PSA_AEAD_ENCRYPT_OUTPUT_SIZE(\p alg, \p plaintext_length).
+ * See also #PSA_AEAD_ENCRYPT_OUTPUT_SIZE(\p key_type, \p alg,
+ * \p plaintext_length).
  *
  * \param plaintext_length    Size of the plaintext in bytes.
  *
@@ -287,10 +303,14 @@
  * insufficient buffer size. Depending on the algorithm, the actual size of
  * the plaintext may be smaller.
  *
+ * See also #PSA_AEAD_DECRYPT_OUTPUT_MAX_SIZE(\p ciphertext_length).
+ *
  * \warning This macro may evaluate its arguments multiple times or
  *          zero times, so you should not pass arguments that contain
  *          side effects.
  *
+ * \param key_type            A symmetric key type that is
+ *                            compatible with algorithm \p alg.
  * \param alg                 An AEAD algorithm
  *                            (\c PSA_ALG_XXX value such that
  *                            #PSA_ALG_IS_AEAD(\p alg) is true).
@@ -298,11 +318,14 @@
  *
  * \return                    The AEAD ciphertext size for the specified
  *                            algorithm.
- *                            If the AEAD algorithm is not recognized, return 0.
+ *                            If the key type or AEAD algorithm is not
+ *                            recognized, or the parameters are incompatible,
+ *                            return 0.
  */
-#define PSA_AEAD_DECRYPT_OUTPUT_SIZE(alg, ciphertext_length)      \
-    (PSA_AEAD_TAG_LENGTH(alg) != 0 ?                              \
-     (ciphertext_length) - PSA_AEAD_TAG_LENGTH(alg) :             \
+#define PSA_AEAD_DECRYPT_OUTPUT_SIZE(key_type, alg, ciphertext_length) \
+    (PSA_AEAD_NONCE_LENGTH(key_type, alg) != 0 &&                      \
+         (ciphertext_length) > PSA_ALG_AEAD_GET_TAG_LENGTH(alg) ?      \
+         (ciphertext_length) - PSA_ALG_AEAD_GET_TAG_LENGTH(alg) :      \
      0)
 
 /** A sufficient output buffer size for psa_aead_decrypt(), for any of the
@@ -314,7 +337,8 @@
  * \note This macro returns a compile-time constant if its arguments are
  *       compile-time constants.
  *
- * See also #PSA_AEAD_DECRYPT_OUTPUT_SIZE(\p alg, \p ciphertext_length).
+ * See also #PSA_AEAD_DECRYPT_OUTPUT_SIZE(\p key_type, \p alg,
+ * \p ciphertext_length).
  *
  * \param ciphertext_length   Size of the ciphertext in bytes.
  *
@@ -352,11 +376,11 @@
  */
 #define PSA_AEAD_NONCE_LENGTH(key_type, alg) \
     (PSA_BLOCK_CIPHER_BLOCK_LENGTH(key_type) == 16 ? \
-          PSA_ALG_AEAD_WITH_DEFAULT_LENGTH_TAG(alg) == PSA_ALG_CCM ? 13 : \
-          PSA_ALG_AEAD_WITH_DEFAULT_LENGTH_TAG(alg) == PSA_ALG_GCM ? 12 : \
+          MBEDTLS_PSA_ALG_AEAD_EQUAL(alg, PSA_ALG_CCM) ? 13 : \
+          MBEDTLS_PSA_ALG_AEAD_EQUAL(alg, PSA_ALG_GCM) ? 12 : \
           0 : \
      (key_type) == PSA_KEY_TYPE_CHACHA20 && \
-          PSA_ALG_AEAD_WITH_DEFAULT_LENGTH_TAG(alg) == PSA_ALG_CHACHA20_POLY1305 ? 12 : \
+          MBEDTLS_PSA_ALG_AEAD_EQUAL(alg, PSA_ALG_CHACHA20_POLY1305) ? 12 : \
      0)
 
 /** The maximum default nonce size among all supported pairs of key types and
@@ -379,10 +403,14 @@
  * insufficient buffer size. The actual size of the output may be smaller
  * in any given call.
  *
+ * See also #PSA_AEAD_UPDATE_OUTPUT_MAX_SIZE(\p input_length).
+ *
  * \warning This macro may evaluate its arguments multiple times or
  *          zero times, so you should not pass arguments that contain
  *          side effects.
  *
+ * \param key_type            A symmetric key type that is
+ *                            compatible with algorithm \p alg.
  * \param alg                 An AEAD algorithm
  *                            (\c PSA_ALG_XXX value such that
  *                            #PSA_ALG_IS_AEAD(\p alg) is true).
@@ -390,16 +418,20 @@
  *
  * \return                    A sufficient output buffer size for the specified
  *                            algorithm.
- *                            If the AEAD algorithm is not recognized, return 0.
+ *                            If the key type or AEAD algorithm is not
+ *                            recognized, or the parameters are incompatible,
+ *                            return 0.
  */
 /* For all the AEAD modes defined in this specification, it is possible
  * to emit output without delay. However, hardware may not always be
  * capable of this. So for modes based on a block cipher, allow the
  * implementation to delay the output until it has a full block. */
-#define PSA_AEAD_UPDATE_OUTPUT_SIZE(alg, input_length)                              \
-    (PSA_ALG_IS_AEAD_ON_BLOCK_CIPHER(alg) ?                                         \
-     PSA_ROUND_UP_TO_MULTIPLE(PSA_BLOCK_CIPHER_BLOCK_MAX_SIZE, (input_length)) :    \
-     (input_length))
+#define PSA_AEAD_UPDATE_OUTPUT_SIZE(key_type, alg, input_length)                             \
+    (PSA_AEAD_NONCE_LENGTH(key_type, alg) != 0 ?                                             \
+         PSA_ALG_IS_AEAD_ON_BLOCK_CIPHER(alg) ?                                              \
+         PSA_ROUND_UP_TO_MULTIPLE(PSA_BLOCK_CIPHER_BLOCK_LENGTH(key_type), (input_length)) : \
+         (input_length) : \
+     0)
 
 /** A sufficient output buffer size for psa_aead_update(), for any of the
  *  supported key types and AEAD algorithms.
@@ -407,7 +439,7 @@
  * If the size of the output buffer is at least this large, it is guaranteed
  * that psa_aead_update() will not fail due to an insufficient buffer size.
  *
- * See also #PSA_AEAD_UPDATE_OUTPUT_SIZE(\p alg, \p input_length).
+ * See also #PSA_AEAD_UPDATE_OUTPUT_SIZE(\p key_type, \p alg, \p input_length).
  *
  * \param input_length      Size of the input in bytes.
  */
@@ -421,23 +453,30 @@
  * insufficient ciphertext buffer size. The actual size of the output may
  * be smaller in any given call.
  *
+ * See also #PSA_AEAD_FINISH_OUTPUT_MAX_SIZE.
+ *
+ * \param key_type            A symmetric key type that is
+                              compatible with algorithm \p alg.
  * \param alg                 An AEAD algorithm
  *                            (\c PSA_ALG_XXX value such that
  *                            #PSA_ALG_IS_AEAD(\p alg) is true).
  *
  * \return                    A sufficient ciphertext buffer size for the
  *                            specified algorithm.
- *                            If the AEAD algorithm is not recognized, return 0.
+ *                            If the key type or AEAD algorithm is not
+ *                            recognized, or the parameters are incompatible,
+ *                            return 0.
  */
-#define PSA_AEAD_FINISH_OUTPUT_SIZE(alg)                                \
-    (PSA_ALG_IS_AEAD_ON_BLOCK_CIPHER(alg) ?                             \
-     PSA_BLOCK_CIPHER_BLOCK_MAX_SIZE :                                  \
+#define PSA_AEAD_FINISH_OUTPUT_SIZE(key_type, alg) \
+    (PSA_AEAD_NONCE_LENGTH(key_type, alg) != 0 &&  \
+         PSA_ALG_IS_AEAD_ON_BLOCK_CIPHER(alg) ?    \
+         PSA_BLOCK_CIPHER_BLOCK_LENGTH(key_type) : \
      0)
 
 /** A sufficient ciphertext buffer size for psa_aead_finish(), for any of the
  *  supported key types and AEAD algorithms.
  *
- * See also #PSA_AEAD_FINISH_OUTPUT_SIZE(\p alg).
+ * See also #PSA_AEAD_FINISH_OUTPUT_SIZE(\p key_type, \p alg).
  */
 #define PSA_AEAD_FINISH_OUTPUT_MAX_SIZE     (PSA_BLOCK_CIPHER_BLOCK_MAX_SIZE)
 
@@ -448,23 +487,30 @@
  * insufficient plaintext buffer size. The actual size of the output may
  * be smaller in any given call.
  *
+ * See also #PSA_AEAD_VERIFY_OUTPUT_MAX_SIZE.
+ *
+ * \param key_type            A symmetric key type that is
+ *                            compatible with algorithm \p alg.
  * \param alg                 An AEAD algorithm
  *                            (\c PSA_ALG_XXX value such that
  *                            #PSA_ALG_IS_AEAD(\p alg) is true).
  *
  * \return                    A sufficient plaintext buffer size for the
  *                            specified algorithm.
- *                            If the AEAD algorithm is not recognized, return 0.
+ *                            If the key type or AEAD algorithm is not
+ *                            recognized, or the parameters are incompatible,
+ *                            return 0.
  */
-#define PSA_AEAD_VERIFY_OUTPUT_SIZE(alg)                                \
-    (PSA_ALG_IS_AEAD_ON_BLOCK_CIPHER(alg) ?                             \
-     PSA_BLOCK_CIPHER_BLOCK_MAX_SIZE :                                  \
+#define PSA_AEAD_VERIFY_OUTPUT_SIZE(key_type, alg) \
+    (PSA_AEAD_NONCE_LENGTH(key_type, alg) != 0 &&  \
+         PSA_ALG_IS_AEAD_ON_BLOCK_CIPHER(alg) ?    \
+         PSA_BLOCK_CIPHER_BLOCK_LENGTH(key_type) : \
      0)
 
 /** A sufficient plaintext buffer size for psa_aead_verify(), for any of the
  *  supported key types and AEAD algorithms.
  *
- * See also #PSA_AEAD_VERIFY_OUTPUT_SIZE(\p alg).
+ * See also #PSA_AEAD_VERIFY_OUTPUT_SIZE(\p key_type, \p alg).
  */
 #define PSA_AEAD_VERIFY_OUTPUT_MAX_SIZE     (PSA_BLOCK_CIPHER_BLOCK_MAX_SIZE)
 
diff --git a/include/psa/crypto_values.h b/include/psa/crypto_values.h
index 5e865c9..9bfd5ab 100644
--- a/include/psa/crypto_values.h
+++ b/include/psa/crypto_values.h
@@ -2137,4 +2137,27 @@
 
 /**@}*/
 
+/** \defgroup helper_macros Helper macros
+ * @{
+ */
+
+/* Helper macros */
+
+/** Check if two AEAD algorithm identifiers refer to the same AEAD algorithm
+ *  regardless of the tag length they encode.
+ *
+ * \param aead_alg_1 An AEAD algorithm identifier.
+ * \param aead_alg_2 An AEAD algorithm identifier.
+ *
+ * \return           1 if both identifiers refer to the same AEAD algorithm,
+ *                   0 otherwise.
+ *                   Unspecified if neither \p aead_alg_1 nor \p aead_alg_2 are
+ *                   a supported AEAD algorithm.
+ */
+#define MBEDTLS_PSA_ALG_AEAD_EQUAL(aead_alg_1, aead_alg_2) \
+    (!(((aead_alg_1) ^ (aead_alg_2)) & \
+       ~(PSA_ALG_AEAD_TAG_LENGTH_MASK | PSA_ALG_AEAD_AT_LEAST_THIS_LENGTH_FLAG)))
+
+/**@}*/
+
 #endif /* PSA_CRYPTO_VALUES_H */
diff --git a/library/dhm.c b/library/dhm.c
index f796812..9758af7 100644
--- a/library/dhm.c
+++ b/library/dhm.c
@@ -79,7 +79,7 @@
         return( MBEDTLS_ERR_DHM_BAD_INPUT_DATA );
 
     if( ( ret = mbedtls_mpi_read_binary( X, *p, n ) ) != 0 )
-        return( MBEDTLS_ERR_DHM_READ_PARAMS_FAILED + ret );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_DHM_READ_PARAMS_FAILED, ret ) );
 
     (*p) += n;
 
@@ -222,7 +222,7 @@
 cleanup:
 
     if( ret != 0 )
-        return( MBEDTLS_ERR_DHM_MAKE_PARAMS_FAILED + ret );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_DHM_MAKE_PARAMS_FAILED, ret ) );
 
     return( 0 );
 }
@@ -242,7 +242,7 @@
     if( ( ret = mbedtls_mpi_copy( &ctx->P, P ) ) != 0 ||
         ( ret = mbedtls_mpi_copy( &ctx->G, G ) ) != 0 )
     {
-        return( MBEDTLS_ERR_DHM_SET_GROUP_FAILED + ret );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_DHM_SET_GROUP_FAILED, ret ) );
     }
 
     ctx->len = mbedtls_mpi_size( &ctx->P );
@@ -263,7 +263,7 @@
         return( MBEDTLS_ERR_DHM_BAD_INPUT_DATA );
 
     if( ( ret = mbedtls_mpi_read_binary( &ctx->GY, input, ilen ) ) != 0 )
-        return( MBEDTLS_ERR_DHM_READ_PUBLIC_FAILED + ret );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_DHM_READ_PUBLIC_FAILED, ret ) );
 
     return( 0 );
 }
@@ -313,7 +313,7 @@
 cleanup:
 
     if( ret != 0 )
-        return( MBEDTLS_ERR_DHM_MAKE_PUBLIC_FAILED + ret );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_DHM_MAKE_PUBLIC_FAILED, ret ) );
 
     return( 0 );
 }
@@ -462,7 +462,7 @@
     mbedtls_mpi_free( &GYb );
 
     if( ret != 0 )
-        return( MBEDTLS_ERR_DHM_CALC_SECRET_FAILED + ret );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_DHM_CALC_SECRET_FAILED, ret ) );
 
     return( 0 );
 }
@@ -544,7 +544,7 @@
     if( ( ret = mbedtls_asn1_get_tag( &p, end, &len,
             MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE ) ) != 0 )
     {
-        ret = MBEDTLS_ERR_DHM_INVALID_FORMAT + ret;
+        ret = MBEDTLS_ERROR_ADD( MBEDTLS_ERR_DHM_INVALID_FORMAT, ret );
         goto exit;
     }
 
@@ -553,7 +553,7 @@
     if( ( ret = mbedtls_asn1_get_mpi( &p, end, &dhm->P  ) ) != 0 ||
         ( ret = mbedtls_asn1_get_mpi( &p, end, &dhm->G ) ) != 0 )
     {
-        ret = MBEDTLS_ERR_DHM_INVALID_FORMAT + ret;
+        ret = MBEDTLS_ERROR_ADD( MBEDTLS_ERR_DHM_INVALID_FORMAT, ret );
         goto exit;
     }
 
@@ -567,13 +567,13 @@
         mbedtls_mpi_free( &rec );
         if ( ret != 0 )
         {
-            ret = MBEDTLS_ERR_DHM_INVALID_FORMAT + ret;
+            ret = MBEDTLS_ERROR_ADD( MBEDTLS_ERR_DHM_INVALID_FORMAT, ret );
             goto exit;
         }
         if ( p != end )
         {
-            ret = MBEDTLS_ERR_DHM_INVALID_FORMAT +
-                MBEDTLS_ERR_ASN1_LENGTH_MISMATCH;
+            ret = MBEDTLS_ERROR_ADD( MBEDTLS_ERR_DHM_INVALID_FORMAT,
+                MBEDTLS_ERR_ASN1_LENGTH_MISMATCH );
             goto exit;
         }
     }
diff --git a/library/ecdsa.c b/library/ecdsa.c
index 7dc8708..7f259e1 100644
--- a/library/ecdsa.c
+++ b/library/ecdsa.c
@@ -870,8 +870,8 @@
 
     if( p + len != end )
     {
-        ret = MBEDTLS_ERR_ECP_BAD_INPUT_DATA +
-              MBEDTLS_ERR_ASN1_LENGTH_MISMATCH;
+        ret = MBEDTLS_ERROR_ADD( MBEDTLS_ERR_ECP_BAD_INPUT_DATA,
+              MBEDTLS_ERR_ASN1_LENGTH_MISMATCH );
         goto cleanup;
     }
 
diff --git a/library/ecp.c b/library/ecp.c
index 4c0d28e..194e448 100644
--- a/library/ecp.c
+++ b/library/ecp.c
@@ -2477,7 +2477,7 @@
 {
 #if defined(MBEDTLS_ECP_RANDOMIZE_MXZ_ALT)
     if( mbedtls_internal_ecp_grp_capable( grp ) )
-        return( mbedtls_internal_ecp_randomize_mxz( grp, P, f_rng, p_rng );
+        return( mbedtls_internal_ecp_randomize_mxz( grp, P, f_rng, p_rng ) );
 #endif /* MBEDTLS_ECP_RANDOMIZE_MXZ_ALT */
 
 #if defined(MBEDTLS_ECP_NO_FALLBACK) && defined(MBEDTLS_ECP_RANDOMIZE_MXZ_ALT)
diff --git a/library/error.c b/library/error.c
index f489be6..a176deb 100644
--- a/library/error.c
+++ b/library/error.c
@@ -858,4 +858,8 @@
 
 #endif /* MBEDTLS_ERROR_C */
 
+#if defined(MBEDTLS_TEST_HOOKS)
+void (*mbedtls_test_hook_error_add)( int, int, const char *, int );
+#endif
+
 #endif /* MBEDTLS_ERROR_C || MBEDTLS_ERROR_STRERROR_DUMMY */
diff --git a/library/pem.c b/library/pem.c
index 969d492..fcfde94 100644
--- a/library/pem.c
+++ b/library/pem.c
@@ -343,7 +343,7 @@
     ret = mbedtls_base64_decode( NULL, 0, &len, s1, s2 - s1 );
 
     if( ret == MBEDTLS_ERR_BASE64_INVALID_CHARACTER )
-        return( MBEDTLS_ERR_PEM_INVALID_DATA + ret );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_PEM_INVALID_DATA, ret ) );
 
     if( ( buf = mbedtls_calloc( 1, len ) ) == NULL )
         return( MBEDTLS_ERR_PEM_ALLOC_FAILED );
@@ -352,7 +352,7 @@
     {
         mbedtls_platform_zeroize( buf, len );
         mbedtls_free( buf );
-        return( MBEDTLS_ERR_PEM_INVALID_DATA + ret );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_PEM_INVALID_DATA, ret ) );
     }
 
     if( enc != 0 )
diff --git a/library/pkcs12.c b/library/pkcs12.c
index 4bdeb68..9823d96 100644
--- a/library/pkcs12.c
+++ b/library/pkcs12.c
@@ -60,21 +60,21 @@
      *
      */
     if( params->tag != ( MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE ) )
-        return( MBEDTLS_ERR_PKCS12_PBE_INVALID_FORMAT +
-                MBEDTLS_ERR_ASN1_UNEXPECTED_TAG );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_PKCS12_PBE_INVALID_FORMAT,
+                MBEDTLS_ERR_ASN1_UNEXPECTED_TAG ) );
 
     if( ( ret = mbedtls_asn1_get_tag( p, end, &salt->len, MBEDTLS_ASN1_OCTET_STRING ) ) != 0 )
-        return( MBEDTLS_ERR_PKCS12_PBE_INVALID_FORMAT + ret );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_PKCS12_PBE_INVALID_FORMAT, ret ) );
 
     salt->p = *p;
     *p += salt->len;
 
     if( ( ret = mbedtls_asn1_get_int( p, end, iterations ) ) != 0 )
-        return( MBEDTLS_ERR_PKCS12_PBE_INVALID_FORMAT + ret );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_PKCS12_PBE_INVALID_FORMAT, ret ) );
 
     if( *p != end )
-        return( MBEDTLS_ERR_PKCS12_PBE_INVALID_FORMAT +
-                MBEDTLS_ERR_ASN1_LENGTH_MISMATCH );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_PKCS12_PBE_INVALID_FORMAT,
+                MBEDTLS_ERR_ASN1_LENGTH_MISMATCH ) );
 
     return( 0 );
 }
diff --git a/library/pkcs5.c b/library/pkcs5.c
index e9e743f..2b014d9 100644
--- a/library/pkcs5.c
+++ b/library/pkcs5.c
@@ -60,8 +60,8 @@
     const unsigned char *end = params->p + params->len;
 
     if( params->tag != ( MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE ) )
-        return( MBEDTLS_ERR_PKCS5_INVALID_FORMAT +
-                MBEDTLS_ERR_ASN1_UNEXPECTED_TAG );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_PKCS5_INVALID_FORMAT,
+                MBEDTLS_ERR_ASN1_UNEXPECTED_TAG ) );
     /*
      *  PBKDF2-params ::= SEQUENCE {
      *    salt              OCTET STRING,
@@ -73,13 +73,13 @@
      */
     if( ( ret = mbedtls_asn1_get_tag( &p, end, &salt->len,
                                       MBEDTLS_ASN1_OCTET_STRING ) ) != 0 )
-        return( MBEDTLS_ERR_PKCS5_INVALID_FORMAT + ret );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_PKCS5_INVALID_FORMAT, ret ) );
 
     salt->p = p;
     p += salt->len;
 
     if( ( ret = mbedtls_asn1_get_int( &p, end, iterations ) ) != 0 )
-        return( MBEDTLS_ERR_PKCS5_INVALID_FORMAT + ret );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_PKCS5_INVALID_FORMAT, ret ) );
 
     if( p == end )
         return( 0 );
@@ -87,21 +87,21 @@
     if( ( ret = mbedtls_asn1_get_int( &p, end, keylen ) ) != 0 )
     {
         if( ret != MBEDTLS_ERR_ASN1_UNEXPECTED_TAG )
-            return( MBEDTLS_ERR_PKCS5_INVALID_FORMAT + ret );
+            return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_PKCS5_INVALID_FORMAT, ret ) );
     }
 
     if( p == end )
         return( 0 );
 
     if( ( ret = mbedtls_asn1_get_alg_null( &p, end, &prf_alg_oid ) ) != 0 )
-        return( MBEDTLS_ERR_PKCS5_INVALID_FORMAT + ret );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_PKCS5_INVALID_FORMAT, ret ) );
 
     if( mbedtls_oid_get_md_hmac( &prf_alg_oid, md_type ) != 0 )
         return( MBEDTLS_ERR_PKCS5_FEATURE_UNAVAILABLE );
 
     if( p != end )
-        return( MBEDTLS_ERR_PKCS5_INVALID_FORMAT +
-                MBEDTLS_ERR_ASN1_LENGTH_MISMATCH );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_PKCS5_INVALID_FORMAT,
+                MBEDTLS_ERR_ASN1_LENGTH_MISMATCH ) );
 
     return( 0 );
 }
@@ -134,12 +134,12 @@
      *  }
      */
     if( pbe_params->tag != ( MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE ) )
-        return( MBEDTLS_ERR_PKCS5_INVALID_FORMAT +
-                MBEDTLS_ERR_ASN1_UNEXPECTED_TAG );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_PKCS5_INVALID_FORMAT,
+                MBEDTLS_ERR_ASN1_UNEXPECTED_TAG ) );
 
     if( ( ret = mbedtls_asn1_get_alg( &p, end, &kdf_alg_oid,
                                       &kdf_alg_params ) ) != 0 )
-        return( MBEDTLS_ERR_PKCS5_INVALID_FORMAT + ret );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_PKCS5_INVALID_FORMAT, ret ) );
 
     // Only PBKDF2 supported at the moment
     //
@@ -160,7 +160,7 @@
     if( ( ret = mbedtls_asn1_get_alg( &p, end, &enc_scheme_oid,
                               &enc_scheme_params ) ) != 0 )
     {
-        return( MBEDTLS_ERR_PKCS5_INVALID_FORMAT + ret );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_PKCS5_INVALID_FORMAT, ret ) );
     }
 
     if( mbedtls_oid_get_cipher_alg( &enc_scheme_oid, &cipher_alg ) != 0 )
diff --git a/library/pkparse.c b/library/pkparse.c
index 0590f2b..3222ca2 100644
--- a/library/pkparse.c
+++ b/library/pkparse.c
@@ -186,8 +186,8 @@
     int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
 
     if ( end - *p < 1 )
-        return( MBEDTLS_ERR_PK_KEY_INVALID_FORMAT +
-                MBEDTLS_ERR_ASN1_OUT_OF_DATA );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_PK_KEY_INVALID_FORMAT,
+                MBEDTLS_ERR_ASN1_OUT_OF_DATA ) );
 
     /* Tag may be either OID or SEQUENCE */
     params->tag = **p;
@@ -197,21 +197,21 @@
 #endif
             )
     {
-        return( MBEDTLS_ERR_PK_KEY_INVALID_FORMAT +
-                MBEDTLS_ERR_ASN1_UNEXPECTED_TAG );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_PK_KEY_INVALID_FORMAT,
+                MBEDTLS_ERR_ASN1_UNEXPECTED_TAG ) );
     }
 
     if( ( ret = mbedtls_asn1_get_tag( p, end, &params->len, params->tag ) ) != 0 )
     {
-        return( MBEDTLS_ERR_PK_KEY_INVALID_FORMAT + ret );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_PK_KEY_INVALID_FORMAT, ret ) );
     }
 
     params->p = *p;
     *p += params->len;
 
     if( *p != end )
-        return( MBEDTLS_ERR_PK_KEY_INVALID_FORMAT +
-                MBEDTLS_ERR_ASN1_LENGTH_MISMATCH );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_PK_KEY_INVALID_FORMAT,
+                MBEDTLS_ERR_ASN1_LENGTH_MISMATCH ) );
 
     return( 0 );
 }
@@ -247,7 +247,7 @@
 
     /* SpecifiedECDomainVersion ::= INTEGER { 1, 2, 3 } */
     if( ( ret = mbedtls_asn1_get_int( &p, end, &ver ) ) != 0 )
-        return( MBEDTLS_ERR_PK_KEY_INVALID_FORMAT + ret );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_PK_KEY_INVALID_FORMAT, ret ) );
 
     if( ver < 1 || ver > 3 )
         return( MBEDTLS_ERR_PK_KEY_INVALID_FORMAT );
@@ -285,13 +285,13 @@
 
     /* Prime-p ::= INTEGER -- Field of size p. */
     if( ( ret = mbedtls_asn1_get_mpi( &p, end_field, &grp->P ) ) != 0 )
-        return( MBEDTLS_ERR_PK_KEY_INVALID_FORMAT + ret );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_PK_KEY_INVALID_FORMAT, ret ) );
 
     grp->pbits = mbedtls_mpi_bitlen( &grp->P );
 
     if( p != end_field )
-        return( MBEDTLS_ERR_PK_KEY_INVALID_FORMAT +
-                MBEDTLS_ERR_ASN1_LENGTH_MISMATCH );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_PK_KEY_INVALID_FORMAT,
+                MBEDTLS_ERR_ASN1_LENGTH_MISMATCH ) );
 
     /*
      * Curve ::= SEQUENCE {
@@ -315,7 +315,7 @@
     if( ( ret = mbedtls_asn1_get_tag( &p, end_curve, &len, MBEDTLS_ASN1_OCTET_STRING ) ) != 0 ||
         ( ret = mbedtls_mpi_read_binary( &grp->A, p, len ) ) != 0 )
     {
-        return( MBEDTLS_ERR_PK_KEY_INVALID_FORMAT + ret );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_PK_KEY_INVALID_FORMAT, ret ) );
     }
 
     p += len;
@@ -323,7 +323,7 @@
     if( ( ret = mbedtls_asn1_get_tag( &p, end_curve, &len, MBEDTLS_ASN1_OCTET_STRING ) ) != 0 ||
         ( ret = mbedtls_mpi_read_binary( &grp->B, p, len ) ) != 0 )
     {
-        return( MBEDTLS_ERR_PK_KEY_INVALID_FORMAT + ret );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_PK_KEY_INVALID_FORMAT, ret ) );
     }
 
     p += len;
@@ -333,14 +333,14 @@
         p += len;
 
     if( p != end_curve )
-        return( MBEDTLS_ERR_PK_KEY_INVALID_FORMAT +
-                MBEDTLS_ERR_ASN1_LENGTH_MISMATCH );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_PK_KEY_INVALID_FORMAT,
+                MBEDTLS_ERR_ASN1_LENGTH_MISMATCH ) );
 
     /*
      * ECPoint ::= OCTET STRING
      */
     if( ( ret = mbedtls_asn1_get_tag( &p, end, &len, MBEDTLS_ASN1_OCTET_STRING ) ) != 0 )
-        return( MBEDTLS_ERR_PK_KEY_INVALID_FORMAT + ret );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_PK_KEY_INVALID_FORMAT, ret ) );
 
     if( ( ret = mbedtls_ecp_point_read_binary( grp, &grp->G,
                                       ( const unsigned char *) p, len ) ) != 0 )
@@ -366,7 +366,7 @@
      * order INTEGER
      */
     if( ( ret = mbedtls_asn1_get_mpi( &p, end, &grp->N ) ) != 0 )
-        return( MBEDTLS_ERR_PK_KEY_INVALID_FORMAT + ret );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_PK_KEY_INVALID_FORMAT, ret ) );
 
     grp->nbits = mbedtls_mpi_bitlen( &grp->N );
 
@@ -528,15 +528,15 @@
 
     if( ( ret = mbedtls_asn1_get_tag( p, end, &len,
             MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE ) ) != 0 )
-        return( MBEDTLS_ERR_PK_INVALID_PUBKEY + ret );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_PK_INVALID_PUBKEY, ret ) );
 
     if( *p + len != end )
-        return( MBEDTLS_ERR_PK_INVALID_PUBKEY +
-                MBEDTLS_ERR_ASN1_LENGTH_MISMATCH );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_PK_INVALID_PUBKEY,
+                MBEDTLS_ERR_ASN1_LENGTH_MISMATCH ) );
 
     /* Import N */
     if( ( ret = mbedtls_asn1_get_tag( p, end, &len, MBEDTLS_ASN1_INTEGER ) ) != 0 )
-        return( MBEDTLS_ERR_PK_INVALID_PUBKEY + ret );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_PK_INVALID_PUBKEY, ret ) );
 
     if( ( ret = mbedtls_rsa_import_raw( rsa, *p, len, NULL, 0, NULL, 0,
                                         NULL, 0, NULL, 0 ) ) != 0 )
@@ -546,7 +546,7 @@
 
     /* Import E */
     if( ( ret = mbedtls_asn1_get_tag( p, end, &len, MBEDTLS_ASN1_INTEGER ) ) != 0 )
-        return( MBEDTLS_ERR_PK_INVALID_PUBKEY + ret );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_PK_INVALID_PUBKEY, ret ) );
 
     if( ( ret = mbedtls_rsa_import_raw( rsa, NULL, 0, NULL, 0, NULL, 0,
                                         NULL, 0, *p, len ) ) != 0 )
@@ -561,8 +561,8 @@
     }
 
     if( *p != end )
-        return( MBEDTLS_ERR_PK_INVALID_PUBKEY +
-                MBEDTLS_ERR_ASN1_LENGTH_MISMATCH );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_PK_INVALID_PUBKEY,
+                MBEDTLS_ERR_ASN1_LENGTH_MISMATCH ) );
 
     return( 0 );
 }
@@ -584,7 +584,7 @@
     memset( params, 0, sizeof(mbedtls_asn1_buf) );
 
     if( ( ret = mbedtls_asn1_get_alg( p, end, &alg_oid, params ) ) != 0 )
-        return( MBEDTLS_ERR_PK_INVALID_ALG + ret );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_PK_INVALID_ALG, ret ) );
 
     if( mbedtls_oid_get_pk_alg( &alg_oid, pk_alg ) != 0 )
         return( MBEDTLS_ERR_PK_UNKNOWN_PK_ALG );
@@ -624,7 +624,7 @@
     if( ( ret = mbedtls_asn1_get_tag( p, end, &len,
                     MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE ) ) != 0 )
     {
-        return( MBEDTLS_ERR_PK_KEY_INVALID_FORMAT + ret );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_PK_KEY_INVALID_FORMAT, ret ) );
     }
 
     end = *p + len;
@@ -633,11 +633,11 @@
         return( ret );
 
     if( ( ret = mbedtls_asn1_get_bitstring_null( p, end, &len ) ) != 0 )
-        return( MBEDTLS_ERR_PK_INVALID_PUBKEY + ret );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_PK_INVALID_PUBKEY, ret ) );
 
     if( *p + len != end )
-        return( MBEDTLS_ERR_PK_INVALID_PUBKEY +
-                MBEDTLS_ERR_ASN1_LENGTH_MISMATCH );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_PK_INVALID_PUBKEY,
+                MBEDTLS_ERR_ASN1_LENGTH_MISMATCH ) );
 
     if( ( pk_info = mbedtls_pk_info_from_type( pk_alg ) ) == NULL )
         return( MBEDTLS_ERR_PK_UNKNOWN_PK_ALG );
@@ -662,8 +662,8 @@
         ret = MBEDTLS_ERR_PK_UNKNOWN_PK_ALG;
 
     if( ret == 0 && *p != end )
-        ret = MBEDTLS_ERR_PK_INVALID_PUBKEY +
-              MBEDTLS_ERR_ASN1_LENGTH_MISMATCH;
+        ret = MBEDTLS_ERROR_ADD( MBEDTLS_ERR_PK_INVALID_PUBKEY,
+              MBEDTLS_ERR_ASN1_LENGTH_MISMATCH );
 
     if( ret != 0 )
         mbedtls_pk_free( pk );
@@ -734,14 +734,14 @@
     if( ( ret = mbedtls_asn1_get_tag( &p, end, &len,
             MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE ) ) != 0 )
     {
-        return( MBEDTLS_ERR_PK_KEY_INVALID_FORMAT + ret );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_PK_KEY_INVALID_FORMAT, ret ) );
     }
 
     end = p + len;
 
     if( ( ret = mbedtls_asn1_get_int( &p, end, &version ) ) != 0 )
     {
-        return( MBEDTLS_ERR_PK_KEY_INVALID_FORMAT + ret );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_PK_KEY_INVALID_FORMAT, ret ) );
     }
 
     if( version != 0 )
@@ -831,8 +831,8 @@
 
     if( p != end )
     {
-        ret = MBEDTLS_ERR_PK_KEY_INVALID_FORMAT +
-              MBEDTLS_ERR_ASN1_LENGTH_MISMATCH ;
+        ret = MBEDTLS_ERROR_ADD( MBEDTLS_ERR_PK_KEY_INVALID_FORMAT,
+              MBEDTLS_ERR_ASN1_LENGTH_MISMATCH );
     }
 
 cleanup:
@@ -843,7 +843,7 @@
     {
         /* Wrap error code if it's coming from a lower level */
         if( ( ret & 0xff80 ) == 0 )
-            ret = MBEDTLS_ERR_PK_KEY_INVALID_FORMAT + ret;
+            ret = MBEDTLS_ERROR_ADD( MBEDTLS_ERR_PK_KEY_INVALID_FORMAT, ret );
         else
             ret = MBEDTLS_ERR_PK_KEY_INVALID_FORMAT;
 
@@ -883,24 +883,24 @@
     if( ( ret = mbedtls_asn1_get_tag( &p, end, &len,
             MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE ) ) != 0 )
     {
-        return( MBEDTLS_ERR_PK_KEY_INVALID_FORMAT + ret );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_PK_KEY_INVALID_FORMAT, ret ) );
     }
 
     end = p + len;
 
     if( ( ret = mbedtls_asn1_get_int( &p, end, &version ) ) != 0 )
-        return( MBEDTLS_ERR_PK_KEY_INVALID_FORMAT + ret );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_PK_KEY_INVALID_FORMAT, ret ) );
 
     if( version != 1 )
         return( MBEDTLS_ERR_PK_KEY_INVALID_VERSION );
 
     if( ( ret = mbedtls_asn1_get_tag( &p, end, &len, MBEDTLS_ASN1_OCTET_STRING ) ) != 0 )
-        return( MBEDTLS_ERR_PK_KEY_INVALID_FORMAT + ret );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_PK_KEY_INVALID_FORMAT, ret ) );
 
     if( ( ret = mbedtls_mpi_read_binary( &eck->d, p, len ) ) != 0 )
     {
         mbedtls_ecp_keypair_free( eck );
-        return( MBEDTLS_ERR_PK_KEY_INVALID_FORMAT + ret );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_PK_KEY_INVALID_FORMAT, ret ) );
     }
 
     p += len;
@@ -924,7 +924,7 @@
         else if( ret != MBEDTLS_ERR_ASN1_UNEXPECTED_TAG )
         {
             mbedtls_ecp_keypair_free( eck );
-            return( MBEDTLS_ERR_PK_KEY_INVALID_FORMAT + ret );
+            return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_PK_KEY_INVALID_FORMAT, ret ) );
         }
     }
 
@@ -940,11 +940,11 @@
             end2 = p + len;
 
             if( ( ret = mbedtls_asn1_get_bitstring_null( &p, end2, &len ) ) != 0 )
-                return( MBEDTLS_ERR_PK_KEY_INVALID_FORMAT + ret );
+                return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_PK_KEY_INVALID_FORMAT, ret ) );
 
             if( p + len != end2 )
-                return( MBEDTLS_ERR_PK_KEY_INVALID_FORMAT +
-                        MBEDTLS_ERR_ASN1_LENGTH_MISMATCH );
+                return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_PK_KEY_INVALID_FORMAT,
+                        MBEDTLS_ERR_ASN1_LENGTH_MISMATCH ) );
 
             if( ( ret = pk_get_ecpubkey( &p, end2, eck ) ) == 0 )
                 pubkey_done = 1;
@@ -961,7 +961,7 @@
         else if( ret != MBEDTLS_ERR_ASN1_UNEXPECTED_TAG )
         {
             mbedtls_ecp_keypair_free( eck );
-            return( MBEDTLS_ERR_PK_KEY_INVALID_FORMAT + ret );
+            return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_PK_KEY_INVALID_FORMAT, ret ) );
         }
     }
 
@@ -970,7 +970,7 @@
                                                       NULL, NULL ) ) != 0 )
     {
         mbedtls_ecp_keypair_free( eck );
-        return( MBEDTLS_ERR_PK_KEY_INVALID_FORMAT + ret );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_PK_KEY_INVALID_FORMAT, ret ) );
     }
 
     if( ( ret = mbedtls_ecp_check_privkey( &eck->grp, &eck->d ) ) != 0 )
@@ -1028,26 +1028,28 @@
     if( ( ret = mbedtls_asn1_get_tag( &p, end, &len,
             MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE ) ) != 0 )
     {
-        return( MBEDTLS_ERR_PK_KEY_INVALID_FORMAT + ret );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_PK_KEY_INVALID_FORMAT, ret ) );
     }
 
     end = p + len;
 
     if( ( ret = mbedtls_asn1_get_int( &p, end, &version ) ) != 0 )
-        return( MBEDTLS_ERR_PK_KEY_INVALID_FORMAT + ret );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_PK_KEY_INVALID_FORMAT, ret ) );
 
     if( version != 0 )
-        return( MBEDTLS_ERR_PK_KEY_INVALID_VERSION + ret );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_PK_KEY_INVALID_VERSION, ret ) );
 
     if( ( ret = pk_get_pk_alg( &p, end, &pk_alg, &params ) ) != 0 )
-        return( MBEDTLS_ERR_PK_KEY_INVALID_FORMAT + ret );
+    {
+        return( ret );
+    }
 
     if( ( ret = mbedtls_asn1_get_tag( &p, end, &len, MBEDTLS_ASN1_OCTET_STRING ) ) != 0 )
-        return( MBEDTLS_ERR_PK_KEY_INVALID_FORMAT + ret );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_PK_KEY_INVALID_FORMAT, ret ) );
 
     if( len < 1 )
-        return( MBEDTLS_ERR_PK_KEY_INVALID_FORMAT +
-                MBEDTLS_ERR_ASN1_OUT_OF_DATA );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_PK_KEY_INVALID_FORMAT,
+                MBEDTLS_ERR_ASN1_OUT_OF_DATA ) );
 
     if( ( pk_info = mbedtls_pk_info_from_type( pk_alg ) ) == NULL )
         return( MBEDTLS_ERR_PK_UNKNOWN_PK_ALG );
@@ -1130,16 +1132,16 @@
     if( ( ret = mbedtls_asn1_get_tag( &p, end, &len,
             MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE ) ) != 0 )
     {
-        return( MBEDTLS_ERR_PK_KEY_INVALID_FORMAT + ret );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_PK_KEY_INVALID_FORMAT, ret ) );
     }
 
     end = p + len;
 
     if( ( ret = mbedtls_asn1_get_alg( &p, end, &pbe_alg_oid, &pbe_params ) ) != 0 )
-        return( MBEDTLS_ERR_PK_KEY_INVALID_FORMAT + ret );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_PK_KEY_INVALID_FORMAT, ret ) );
 
     if( ( ret = mbedtls_asn1_get_tag( &p, end, &len, MBEDTLS_ASN1_OCTET_STRING ) ) != 0 )
-        return( MBEDTLS_ERR_PK_KEY_INVALID_FORMAT + ret );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_PK_KEY_INVALID_FORMAT, ret ) );
 
     buf = p;
 
@@ -1518,7 +1520,8 @@
         return( ret );
     }
     mbedtls_pk_free( ctx );
-    if( ret != ( MBEDTLS_ERR_PK_INVALID_PUBKEY + MBEDTLS_ERR_ASN1_UNEXPECTED_TAG ) )
+    if( ret != ( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_PK_INVALID_PUBKEY,
+                                    MBEDTLS_ERR_ASN1_UNEXPECTED_TAG ) ) )
     {
         return( ret );
     }
diff --git a/library/psa_crypto_aead.c b/library/psa_crypto_aead.c
index 2632830..356679c 100644
--- a/library/psa_crypto_aead.c
+++ b/library/psa_crypto_aead.c
@@ -154,10 +154,14 @@
             return( PSA_ERROR_NOT_SUPPORTED );
     }
 
-    if( PSA_AEAD_TAG_LENGTH( alg ) > full_tag_length )
+    if( PSA_AEAD_TAG_LENGTH( attributes->core.type,
+                             key_bits, alg )
+        > full_tag_length )
         return( PSA_ERROR_INVALID_ARGUMENT );
 
-    operation->tag_length = PSA_AEAD_TAG_LENGTH( alg );
+    operation->tag_length = PSA_AEAD_TAG_LENGTH( attributes->core.type,
+                                                 key_bits,
+                                                 alg );
 
     return( PSA_SUCCESS );
 }
diff --git a/library/rsa.c b/library/rsa.c
index 32eb74e..209273e 100644
--- a/library/rsa.c
+++ b/library/rsa.c
@@ -102,7 +102,7 @@
         ( D != NULL && ( ret = mbedtls_mpi_copy( &ctx->D, D ) ) != 0 ) ||
         ( E != NULL && ( ret = mbedtls_mpi_copy( &ctx->E, E ) ) != 0 ) )
     {
-        return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA + ret );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_RSA_BAD_INPUT_DATA, ret ) );
     }
 
     if( N != NULL )
@@ -142,7 +142,7 @@
 cleanup:
 
     if( ret != 0 )
-        return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA + ret );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_RSA_BAD_INPUT_DATA, ret ) );
 
     return( 0 );
 }
@@ -293,7 +293,7 @@
         if( ( ret = mbedtls_mpi_mul_mpi( &ctx->N, &ctx->P,
                                          &ctx->Q ) ) != 0 )
         {
-            return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA + ret );
+            return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_RSA_BAD_INPUT_DATA, ret ) );
         }
 
         ctx->len = mbedtls_mpi_size( &ctx->N );
@@ -308,7 +308,7 @@
         ret = mbedtls_rsa_deduce_primes( &ctx->N, &ctx->E, &ctx->D,
                                          &ctx->P, &ctx->Q );
         if( ret != 0 )
-            return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA + ret );
+            return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_RSA_BAD_INPUT_DATA, ret ) );
 
     }
     else if( d_missing )
@@ -318,7 +318,7 @@
                                                          &ctx->E,
                                                          &ctx->D ) ) != 0 )
         {
-            return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA + ret );
+            return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_RSA_BAD_INPUT_DATA, ret ) );
         }
     }
 
@@ -333,7 +333,7 @@
         ret = mbedtls_rsa_deduce_crt( &ctx->P,  &ctx->Q,  &ctx->D,
                                       &ctx->DP, &ctx->DQ, &ctx->QP );
         if( ret != 0 )
-            return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA + ret );
+            return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_RSA_BAD_INPUT_DATA, ret ) );
     }
 #endif /* MBEDTLS_RSA_NO_CRT */
 
@@ -461,13 +461,13 @@
         ( DQ != NULL && ( ret = mbedtls_mpi_copy( DQ, &ctx->DQ ) ) != 0 ) ||
         ( QP != NULL && ( ret = mbedtls_mpi_copy( QP, &ctx->QP ) ) != 0 ) )
     {
-        return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA + ret );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_RSA_BAD_INPUT_DATA, ret ) );
     }
 #else
     if( ( ret = mbedtls_rsa_deduce_crt( &ctx->P, &ctx->Q, &ctx->D,
                                         DP, DQ, QP ) ) != 0 )
     {
-        return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA + ret );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_RSA_BAD_INPUT_DATA, ret ) );
     }
 #endif
 
@@ -635,8 +635,9 @@
     if( ret != 0 )
     {
         mbedtls_rsa_free( ctx );
+
         if( ( -ret & ~0x7f ) == 0 )
-            ret = MBEDTLS_ERR_RSA_KEY_GEN_FAILED + ret;
+            ret = MBEDTLS_ERROR_ADD( MBEDTLS_ERR_RSA_KEY_GEN_FAILED, ret );
         return( ret );
     }
 
@@ -769,7 +770,7 @@
     mbedtls_mpi_free( &T );
 
     if( ret != 0 )
-        return( MBEDTLS_ERR_RSA_PUBLIC_FAILED + ret );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_RSA_PUBLIC_FAILED, ret ) );
 
     return( 0 );
 }
@@ -1085,7 +1086,7 @@
     mbedtls_mpi_free( &I );
 
     if( ret != 0 && ret >= -0x007f )
-        return( MBEDTLS_ERR_RSA_PRIVATE_FAILED + ret );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_RSA_PRIVATE_FAILED, ret ) );
 
     return( ret );
 }
@@ -1198,7 +1199,7 @@
 
     /* Generate a random octet string seed */
     if( ( ret = f_rng( p_rng, p, hlen ) ) != 0 )
-        return( MBEDTLS_ERR_RSA_RNG_FAILED + ret );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_RSA_RNG_FAILED, ret ) );
 
     p += hlen;
 
@@ -1287,7 +1288,7 @@
 
             /* Check if RNG failed to generate data */
             if( rng_dl == 0 || ret != 0 )
-                return( MBEDTLS_ERR_RSA_RNG_FAILED + ret );
+                return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_RSA_RNG_FAILED, ret ) );
 
             p++;
         }
@@ -1881,7 +1882,7 @@
     /* Generate salt of length slen in place in the encoded message */
     salt = p;
     if( ( ret = f_rng( p_rng, salt, slen ) ) != 0 )
-        return( MBEDTLS_ERR_RSA_RNG_FAILED + ret );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_RSA_RNG_FAILED, ret ) );
 
     p += slen;
 
diff --git a/library/ssl_cookie.c b/library/ssl_cookie.c
index fa89a07..1cfab87 100644
--- a/library/ssl_cookie.c
+++ b/library/ssl_cookie.c
@@ -174,7 +174,7 @@
 
 #if defined(MBEDTLS_THREADING_C)
     if( ( ret = mbedtls_mutex_lock( &ctx->mutex ) ) != 0 )
-        return( MBEDTLS_ERR_SSL_INTERNAL_ERROR + ret );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_SSL_INTERNAL_ERROR, ret ) );
 #endif
 
     ret = ssl_cookie_hmac( &ctx->hmac_ctx, *p - 4,
@@ -182,8 +182,8 @@
 
 #if defined(MBEDTLS_THREADING_C)
     if( mbedtls_mutex_unlock( &ctx->mutex ) != 0 )
-        return( MBEDTLS_ERR_SSL_INTERNAL_ERROR +
-                MBEDTLS_ERR_THREADING_MUTEX_ERROR );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_SSL_INTERNAL_ERROR,
+                MBEDTLS_ERR_THREADING_MUTEX_ERROR ) );
 #endif
 
     return( ret );
@@ -210,7 +210,7 @@
 
 #if defined(MBEDTLS_THREADING_C)
     if( ( ret = mbedtls_mutex_lock( &ctx->mutex ) ) != 0 )
-        return( MBEDTLS_ERR_SSL_INTERNAL_ERROR + ret );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_SSL_INTERNAL_ERROR, ret ) );
 #endif
 
     if( ssl_cookie_hmac( &ctx->hmac_ctx, cookie,
@@ -220,8 +220,8 @@
 
 #if defined(MBEDTLS_THREADING_C)
     if( mbedtls_mutex_unlock( &ctx->mutex ) != 0 )
-        return( MBEDTLS_ERR_SSL_INTERNAL_ERROR +
-                MBEDTLS_ERR_THREADING_MUTEX_ERROR );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_SSL_INTERNAL_ERROR,
+                MBEDTLS_ERR_THREADING_MUTEX_ERROR ) );
 #endif
 
     if( ret != 0 )
diff --git a/library/x509.c b/library/x509.c
index d63a430..2e11c7f 100644
--- a/library/x509.c
+++ b/library/x509.c
@@ -81,18 +81,18 @@
     int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
 
     if( ( end - *p ) < 1 )
-        return( MBEDTLS_ERR_X509_INVALID_SERIAL +
-                MBEDTLS_ERR_ASN1_OUT_OF_DATA );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_SERIAL,
+                MBEDTLS_ERR_ASN1_OUT_OF_DATA ) );
 
     if( **p != ( MBEDTLS_ASN1_CONTEXT_SPECIFIC | MBEDTLS_ASN1_PRIMITIVE | 2 ) &&
         **p !=   MBEDTLS_ASN1_INTEGER )
-        return( MBEDTLS_ERR_X509_INVALID_SERIAL +
-                MBEDTLS_ERR_ASN1_UNEXPECTED_TAG );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_SERIAL,
+                MBEDTLS_ERR_ASN1_UNEXPECTED_TAG ) );
 
     serial->tag = *(*p)++;
 
     if( ( ret = mbedtls_asn1_get_len( p, end, &serial->len ) ) != 0 )
-        return( MBEDTLS_ERR_X509_INVALID_SERIAL + ret );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_SERIAL, ret ) );
 
     serial->p = *p;
     *p += serial->len;
@@ -112,7 +112,7 @@
     int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
 
     if( ( ret = mbedtls_asn1_get_alg_null( p, end, alg ) ) != 0 )
-        return( MBEDTLS_ERR_X509_INVALID_ALG + ret );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_ALG, ret ) );
 
     return( 0 );
 }
@@ -126,7 +126,7 @@
     int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
 
     if( ( ret = mbedtls_asn1_get_alg( p, end, alg, params ) ) != 0 )
-        return( MBEDTLS_ERR_X509_INVALID_ALG + ret );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_ALG, ret ) );
 
     return( 0 );
 }
@@ -151,39 +151,39 @@
 
     /* Make sure we got a SEQUENCE and setup bounds */
     if( alg->tag != ( MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE ) )
-        return( MBEDTLS_ERR_X509_INVALID_ALG +
-                MBEDTLS_ERR_ASN1_UNEXPECTED_TAG );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_ALG,
+                MBEDTLS_ERR_ASN1_UNEXPECTED_TAG ) );
 
     p = alg->p;
     end = p + alg->len;
 
     if( p >= end )
-        return( MBEDTLS_ERR_X509_INVALID_ALG +
-                MBEDTLS_ERR_ASN1_OUT_OF_DATA );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_ALG,
+                MBEDTLS_ERR_ASN1_OUT_OF_DATA ) );
 
     /* Parse md_oid */
     md_oid.tag = *p;
 
     if( ( ret = mbedtls_asn1_get_tag( &p, end, &md_oid.len, MBEDTLS_ASN1_OID ) ) != 0 )
-        return( MBEDTLS_ERR_X509_INVALID_ALG + ret );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_ALG, ret ) );
 
     md_oid.p = p;
     p += md_oid.len;
 
     /* Get md_alg from md_oid */
     if( ( ret = mbedtls_oid_get_md_alg( &md_oid, md_alg ) ) != 0 )
-        return( MBEDTLS_ERR_X509_INVALID_ALG + ret );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_ALG, ret ) );
 
     /* Make sure params is absent of NULL */
     if( p == end )
         return( 0 );
 
     if( ( ret = mbedtls_asn1_get_tag( &p, end, &len, MBEDTLS_ASN1_NULL ) ) != 0 || len != 0 )
-        return( MBEDTLS_ERR_X509_INVALID_ALG + ret );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_ALG, ret ) );
 
     if( p != end )
-        return( MBEDTLS_ERR_X509_INVALID_ALG +
-                MBEDTLS_ERR_ASN1_LENGTH_MISMATCH );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_ALG,
+                MBEDTLS_ERR_ASN1_LENGTH_MISMATCH ) );
 
     return( 0 );
 }
@@ -217,8 +217,8 @@
 
     /* Make sure params is a SEQUENCE and setup bounds */
     if( params->tag != ( MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE ) )
-        return( MBEDTLS_ERR_X509_INVALID_ALG +
-                MBEDTLS_ERR_ASN1_UNEXPECTED_TAG );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_ALG,
+                MBEDTLS_ERR_ASN1_UNEXPECTED_TAG ) );
 
     p = (unsigned char *) params->p;
     end = p + params->len;
@@ -239,14 +239,14 @@
             return( ret );
 
         if( ( ret = mbedtls_oid_get_md_alg( &alg_id, md_alg ) ) != 0 )
-            return( MBEDTLS_ERR_X509_INVALID_ALG + ret );
+            return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_ALG, ret ) );
 
         if( p != end2 )
-            return( MBEDTLS_ERR_X509_INVALID_ALG +
-                    MBEDTLS_ERR_ASN1_LENGTH_MISMATCH );
+            return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_ALG,
+                    MBEDTLS_ERR_ASN1_LENGTH_MISMATCH ) );
     }
     else if( ret != MBEDTLS_ERR_ASN1_UNEXPECTED_TAG )
-        return( MBEDTLS_ERR_X509_INVALID_ALG + ret );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_ALG, ret ) );
 
     if( p == end )
         return( 0 );
@@ -265,19 +265,19 @@
 
         /* Only MFG1 is recognised for now */
         if( MBEDTLS_OID_CMP( MBEDTLS_OID_MGF1, &alg_id ) != 0 )
-            return( MBEDTLS_ERR_X509_FEATURE_UNAVAILABLE +
-                    MBEDTLS_ERR_OID_NOT_FOUND );
+            return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_FEATURE_UNAVAILABLE,
+                    MBEDTLS_ERR_OID_NOT_FOUND ) );
 
         /* Parse HashAlgorithm */
         if( ( ret = x509_get_hash_alg( &alg_params, mgf_md ) ) != 0 )
             return( ret );
 
         if( p != end2 )
-            return( MBEDTLS_ERR_X509_INVALID_ALG +
-                    MBEDTLS_ERR_ASN1_LENGTH_MISMATCH );
+            return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_ALG,
+                    MBEDTLS_ERR_ASN1_LENGTH_MISMATCH ) );
     }
     else if( ret != MBEDTLS_ERR_ASN1_UNEXPECTED_TAG )
-        return( MBEDTLS_ERR_X509_INVALID_ALG + ret );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_ALG, ret ) );
 
     if( p == end )
         return( 0 );
@@ -291,14 +291,14 @@
         end2 = p + len;
 
         if( ( ret = mbedtls_asn1_get_int( &p, end2, salt_len ) ) != 0 )
-            return( MBEDTLS_ERR_X509_INVALID_ALG + ret );
+            return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_ALG, ret ) );
 
         if( p != end2 )
-            return( MBEDTLS_ERR_X509_INVALID_ALG +
-                    MBEDTLS_ERR_ASN1_LENGTH_MISMATCH );
+            return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_ALG,
+                    MBEDTLS_ERR_ASN1_LENGTH_MISMATCH ) );
     }
     else if( ret != MBEDTLS_ERR_ASN1_UNEXPECTED_TAG )
-        return( MBEDTLS_ERR_X509_INVALID_ALG + ret );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_ALG, ret ) );
 
     if( p == end )
         return( 0 );
@@ -314,21 +314,21 @@
         end2 = p + len;
 
         if( ( ret = mbedtls_asn1_get_int( &p, end2, &trailer_field ) ) != 0 )
-            return( MBEDTLS_ERR_X509_INVALID_ALG + ret );
+            return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_ALG, ret ) );
 
         if( p != end2 )
-            return( MBEDTLS_ERR_X509_INVALID_ALG +
-                    MBEDTLS_ERR_ASN1_LENGTH_MISMATCH );
+            return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_ALG,
+                    MBEDTLS_ERR_ASN1_LENGTH_MISMATCH ) );
 
         if( trailer_field != 1 )
             return( MBEDTLS_ERR_X509_INVALID_ALG );
     }
     else if( ret != MBEDTLS_ERR_ASN1_UNEXPECTED_TAG )
-        return( MBEDTLS_ERR_X509_INVALID_ALG + ret );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_ALG, ret ) );
 
     if( p != end )
-        return( MBEDTLS_ERR_X509_INVALID_ALG +
-                MBEDTLS_ERR_ASN1_LENGTH_MISMATCH );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_ALG,
+                MBEDTLS_ERR_ASN1_LENGTH_MISMATCH ) );
 
     return( 0 );
 }
@@ -354,47 +354,47 @@
 
     if( ( ret = mbedtls_asn1_get_tag( p, end, &len,
             MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE ) ) != 0 )
-        return( MBEDTLS_ERR_X509_INVALID_NAME + ret );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_NAME, ret ) );
 
     end = *p + len;
 
     if( ( end - *p ) < 1 )
-        return( MBEDTLS_ERR_X509_INVALID_NAME +
-                MBEDTLS_ERR_ASN1_OUT_OF_DATA );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_NAME,
+                MBEDTLS_ERR_ASN1_OUT_OF_DATA ) );
 
     oid = &cur->oid;
     oid->tag = **p;
 
     if( ( ret = mbedtls_asn1_get_tag( p, end, &oid->len, MBEDTLS_ASN1_OID ) ) != 0 )
-        return( MBEDTLS_ERR_X509_INVALID_NAME + ret );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_NAME, ret ) );
 
     oid->p = *p;
     *p += oid->len;
 
     if( ( end - *p ) < 1 )
-        return( MBEDTLS_ERR_X509_INVALID_NAME +
-                MBEDTLS_ERR_ASN1_OUT_OF_DATA );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_NAME,
+                MBEDTLS_ERR_ASN1_OUT_OF_DATA ) );
 
     if( **p != MBEDTLS_ASN1_BMP_STRING && **p != MBEDTLS_ASN1_UTF8_STRING      &&
         **p != MBEDTLS_ASN1_T61_STRING && **p != MBEDTLS_ASN1_PRINTABLE_STRING &&
         **p != MBEDTLS_ASN1_IA5_STRING && **p != MBEDTLS_ASN1_UNIVERSAL_STRING &&
         **p != MBEDTLS_ASN1_BIT_STRING )
-        return( MBEDTLS_ERR_X509_INVALID_NAME +
-                MBEDTLS_ERR_ASN1_UNEXPECTED_TAG );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_NAME,
+                MBEDTLS_ERR_ASN1_UNEXPECTED_TAG ) );
 
     val = &cur->val;
     val->tag = *(*p)++;
 
     if( ( ret = mbedtls_asn1_get_len( p, end, &val->len ) ) != 0 )
-        return( MBEDTLS_ERR_X509_INVALID_NAME + ret );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_NAME, ret ) );
 
     val->p = *p;
     *p += val->len;
 
     if( *p != end )
     {
-        return( MBEDTLS_ERR_X509_INVALID_NAME +
-                MBEDTLS_ERR_ASN1_LENGTH_MISMATCH );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_NAME,
+                MBEDTLS_ERR_ASN1_LENGTH_MISMATCH ) );
     }
 
     cur->next = NULL;
@@ -440,7 +440,7 @@
          */
         if( ( ret = mbedtls_asn1_get_tag( p, end, &set_len,
                 MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SET ) ) != 0 )
-            return( MBEDTLS_ERR_X509_INVALID_NAME + ret );
+            return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_NAME, ret ) );
 
         end_set  = *p + set_len;
 
@@ -604,8 +604,8 @@
     unsigned char tag;
 
     if( ( end - *p ) < 1 )
-        return( MBEDTLS_ERR_X509_INVALID_DATE +
-                MBEDTLS_ERR_ASN1_OUT_OF_DATA );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_DATE,
+                MBEDTLS_ERR_ASN1_OUT_OF_DATA ) );
 
     tag = **p;
 
@@ -614,14 +614,14 @@
     else if( tag == MBEDTLS_ASN1_GENERALIZED_TIME )
         year_len = 4;
     else
-        return( MBEDTLS_ERR_X509_INVALID_DATE +
-                MBEDTLS_ERR_ASN1_UNEXPECTED_TAG );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_DATE,
+                MBEDTLS_ERR_ASN1_UNEXPECTED_TAG ) );
 
     (*p)++;
     ret = mbedtls_asn1_get_len( p, end, &len );
 
     if( ret != 0 )
-        return( MBEDTLS_ERR_X509_INVALID_DATE + ret );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_DATE, ret ) );
 
     return x509_parse_time( p, len, year_len, tm );
 }
@@ -633,13 +633,13 @@
     int tag_type;
 
     if( ( end - *p ) < 1 )
-        return( MBEDTLS_ERR_X509_INVALID_SIGNATURE +
-                MBEDTLS_ERR_ASN1_OUT_OF_DATA );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_SIGNATURE,
+                MBEDTLS_ERR_ASN1_OUT_OF_DATA ) );
 
     tag_type = **p;
 
     if( ( ret = mbedtls_asn1_get_bitstring_null( p, end, &len ) ) != 0 )
-        return( MBEDTLS_ERR_X509_INVALID_SIGNATURE + ret );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_SIGNATURE, ret ) );
 
     sig->tag = tag_type;
     sig->len = len;
@@ -663,7 +663,7 @@
         return( MBEDTLS_ERR_X509_BAD_INPUT_DATA );
 
     if( ( ret = mbedtls_oid_get_sig_alg( sig_oid, md_alg, pk_alg ) ) != 0 )
-        return( MBEDTLS_ERR_X509_UNKNOWN_SIG_ALG + ret );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_UNKNOWN_SIG_ALG, ret ) );
 
 #if defined(MBEDTLS_X509_RSASSA_PSS_SUPPORT)
     if( *pk_alg == MBEDTLS_PK_RSASSA_PSS )
@@ -714,7 +714,7 @@
     ret = mbedtls_asn1_get_tag( p, end, &ext->len,
               MBEDTLS_ASN1_CONTEXT_SPECIFIC | MBEDTLS_ASN1_CONSTRUCTED | tag );
     if( ret != 0 )
-        return( MBEDTLS_ERR_X509_INVALID_EXTENSIONS + ret );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_EXTENSIONS, ret ) );
 
     ext->tag = MBEDTLS_ASN1_CONTEXT_SPECIFIC | MBEDTLS_ASN1_CONSTRUCTED | tag;
     ext->p   = *p;
@@ -725,11 +725,11 @@
      */
     if( ( ret = mbedtls_asn1_get_tag( p, end, &len,
             MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE ) ) != 0 )
-        return( MBEDTLS_ERR_X509_INVALID_EXTENSIONS + ret );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_EXTENSIONS, ret ) );
 
     if( end != *p + len )
-        return( MBEDTLS_ERR_X509_INVALID_EXTENSIONS +
-                MBEDTLS_ERR_ASN1_LENGTH_MISMATCH );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_EXTENSIONS,
+                MBEDTLS_ERR_ASN1_LENGTH_MISMATCH ) );
 
     return( 0 );
 }
diff --git a/library/x509_crl.c b/library/x509_crl.c
index dbaad7d..e6efdca 100644
--- a/library/x509_crl.c
+++ b/library/x509_crl.c
@@ -79,7 +79,7 @@
             return( 0 );
         }
 
-        return( MBEDTLS_ERR_X509_INVALID_VERSION + ret );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_VERSION, ret ) );
     }
 
     return( 0 );
@@ -125,7 +125,7 @@
         /* Get enclosing sequence tag */
         if( ( ret = mbedtls_asn1_get_tag( p, end, &len,
                 MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE ) ) != 0 )
-            return( MBEDTLS_ERR_X509_INVALID_EXTENSIONS + ret );
+            return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_EXTENSIONS, ret ) );
 
         end_ext_data = *p + len;
 
@@ -133,7 +133,7 @@
         if( ( ret = mbedtls_asn1_get_tag( p, end_ext_data, &len,
                                           MBEDTLS_ASN1_OID ) ) != 0 )
         {
-            return( MBEDTLS_ERR_X509_INVALID_EXTENSIONS + ret );
+            return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_EXTENSIONS, ret ) );
         }
         *p += len;
 
@@ -142,29 +142,29 @@
                                            &is_critical ) ) != 0 &&
             ( ret != MBEDTLS_ERR_ASN1_UNEXPECTED_TAG ) )
         {
-            return( MBEDTLS_ERR_X509_INVALID_EXTENSIONS + ret );
+            return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_EXTENSIONS, ret ) );
         }
 
         /* Data should be octet string type */
         if( ( ret = mbedtls_asn1_get_tag( p, end_ext_data, &len,
                 MBEDTLS_ASN1_OCTET_STRING ) ) != 0 )
-            return( MBEDTLS_ERR_X509_INVALID_EXTENSIONS + ret );
+            return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_EXTENSIONS, ret ) );
 
         /* Ignore data so far and just check its length */
         *p += len;
         if( *p != end_ext_data )
-            return( MBEDTLS_ERR_X509_INVALID_EXTENSIONS +
-                    MBEDTLS_ERR_ASN1_LENGTH_MISMATCH );
+            return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_EXTENSIONS,
+                    MBEDTLS_ERR_ASN1_LENGTH_MISMATCH ) );
 
         /* Abort on (unsupported) critical extensions */
         if( is_critical )
-            return( MBEDTLS_ERR_X509_INVALID_EXTENSIONS +
-                    MBEDTLS_ERR_ASN1_UNEXPECTED_TAG );
+            return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_EXTENSIONS,
+                    MBEDTLS_ERR_ASN1_UNEXPECTED_TAG ) );
     }
 
     if( *p != end )
-        return( MBEDTLS_ERR_X509_INVALID_EXTENSIONS +
-                MBEDTLS_ERR_ASN1_LENGTH_MISMATCH );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_EXTENSIONS,
+                MBEDTLS_ERR_ASN1_LENGTH_MISMATCH ) );
 
     return( 0 );
 }
@@ -198,27 +198,27 @@
             ext->p = NULL;
             return( 0 );
         }
-        return( MBEDTLS_ERR_X509_INVALID_EXTENSIONS + ret );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_EXTENSIONS, ret ) );
     }
 
     end = *p + ext->len;
 
     if( end != *p + ext->len )
-        return( MBEDTLS_ERR_X509_INVALID_EXTENSIONS +
-                MBEDTLS_ERR_ASN1_LENGTH_MISMATCH );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_EXTENSIONS,
+                MBEDTLS_ERR_ASN1_LENGTH_MISMATCH ) );
 
     while( *p < end )
     {
         if( ( ret = mbedtls_asn1_get_tag( p, end, &len,
                 MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE ) ) != 0 )
-            return( MBEDTLS_ERR_X509_INVALID_EXTENSIONS + ret );
+            return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_EXTENSIONS, ret ) );
 
         *p += len;
     }
 
     if( *p != end )
-        return( MBEDTLS_ERR_X509_INVALID_EXTENSIONS +
-                MBEDTLS_ERR_ASN1_LENGTH_MISMATCH );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_EXTENSIONS,
+                MBEDTLS_ERR_ASN1_LENGTH_MISMATCH ) );
 
     return( 0 );
 }
@@ -364,8 +364,8 @@
     if( len != (size_t) ( end - p ) )
     {
         mbedtls_x509_crl_free( crl );
-        return( MBEDTLS_ERR_X509_INVALID_FORMAT +
-                MBEDTLS_ERR_ASN1_LENGTH_MISMATCH );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_FORMAT,
+                MBEDTLS_ERR_ASN1_LENGTH_MISMATCH ) );
     }
 
     /*
@@ -377,7 +377,7 @@
             MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE ) ) != 0 )
     {
         mbedtls_x509_crl_free( crl );
-        return( MBEDTLS_ERR_X509_INVALID_FORMAT + ret );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_FORMAT, ret ) );
     }
 
     end = p + len;
@@ -421,7 +421,7 @@
             MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE ) ) != 0 )
     {
         mbedtls_x509_crl_free( crl );
-        return( MBEDTLS_ERR_X509_INVALID_FORMAT + ret );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_FORMAT, ret ) );
     }
 
     if( ( ret = mbedtls_x509_get_name( &p, p + len, &crl->issuer ) ) != 0 )
@@ -444,10 +444,10 @@
 
     if( ( ret = mbedtls_x509_get_time( &p, end, &crl->next_update ) ) != 0 )
     {
-        if( ret != ( MBEDTLS_ERR_X509_INVALID_DATE +
-                        MBEDTLS_ERR_ASN1_UNEXPECTED_TAG ) &&
-            ret != ( MBEDTLS_ERR_X509_INVALID_DATE +
-                        MBEDTLS_ERR_ASN1_OUT_OF_DATA ) )
+        if( ret != ( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_DATE,
+                        MBEDTLS_ERR_ASN1_UNEXPECTED_TAG ) ) &&
+            ret != ( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_DATE,
+                        MBEDTLS_ERR_ASN1_OUT_OF_DATA ) ) )
         {
             mbedtls_x509_crl_free( crl );
             return( ret );
@@ -486,8 +486,8 @@
     if( p != end )
     {
         mbedtls_x509_crl_free( crl );
-        return( MBEDTLS_ERR_X509_INVALID_FORMAT +
-                MBEDTLS_ERR_ASN1_LENGTH_MISMATCH );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_FORMAT,
+                MBEDTLS_ERR_ASN1_LENGTH_MISMATCH ) );
     }
 
     end = crl->raw.p + crl->raw.len;
@@ -521,8 +521,8 @@
     if( p != end )
     {
         mbedtls_x509_crl_free( crl );
-        return( MBEDTLS_ERR_X509_INVALID_FORMAT +
-                MBEDTLS_ERR_ASN1_LENGTH_MISMATCH );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_FORMAT,
+                MBEDTLS_ERR_ASN1_LENGTH_MISMATCH ) );
     }
 
     return( 0 );
diff --git a/library/x509_crt.c b/library/x509_crt.c
index 27e3e33..7aefaa7 100644
--- a/library/x509_crt.c
+++ b/library/x509_crt.c
@@ -393,17 +393,17 @@
             return( 0 );
         }
 
-        return( MBEDTLS_ERR_X509_INVALID_FORMAT + ret );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_FORMAT, ret ) );
     }
 
     end = *p + len;
 
     if( ( ret = mbedtls_asn1_get_int( p, end, ver ) ) != 0 )
-        return( MBEDTLS_ERR_X509_INVALID_VERSION + ret );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_VERSION, ret ) );
 
     if( *p != end )
-        return( MBEDTLS_ERR_X509_INVALID_VERSION +
-                MBEDTLS_ERR_ASN1_LENGTH_MISMATCH );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_VERSION,
+                MBEDTLS_ERR_ASN1_LENGTH_MISMATCH ) );
 
     return( 0 );
 }
@@ -423,7 +423,7 @@
 
     if( ( ret = mbedtls_asn1_get_tag( p, end, &len,
             MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE ) ) != 0 )
-        return( MBEDTLS_ERR_X509_INVALID_DATE + ret );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_DATE, ret ) );
 
     end = *p + len;
 
@@ -434,8 +434,8 @@
         return( ret );
 
     if( *p != end )
-        return( MBEDTLS_ERR_X509_INVALID_DATE +
-                MBEDTLS_ERR_ASN1_LENGTH_MISMATCH );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_DATE,
+                MBEDTLS_ERR_ASN1_LENGTH_MISMATCH ) );
 
     return( 0 );
 }
@@ -460,7 +460,7 @@
         if( ret == MBEDTLS_ERR_ASN1_UNEXPECTED_TAG )
             return( 0 );
 
-        return( MBEDTLS_ERR_X509_INVALID_FORMAT + ret );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_FORMAT, ret ) );
     }
 
     uid->p = *p;
@@ -487,7 +487,7 @@
 
     if( ( ret = mbedtls_asn1_get_tag( p, end, &len,
             MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE ) ) != 0 )
-        return( MBEDTLS_ERR_X509_INVALID_EXTENSIONS + ret );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_EXTENSIONS, ret ) );
 
     if( *p == end )
         return( 0 );
@@ -498,7 +498,7 @@
             ret = mbedtls_asn1_get_int( p, end, ca_istrue );
 
         if( ret != 0 )
-            return( MBEDTLS_ERR_X509_INVALID_EXTENSIONS + ret );
+            return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_EXTENSIONS, ret ) );
 
         if( *ca_istrue != 0 )
             *ca_istrue = 1;
@@ -508,17 +508,17 @@
         return( 0 );
 
     if( ( ret = mbedtls_asn1_get_int( p, end, max_pathlen ) ) != 0 )
-        return( MBEDTLS_ERR_X509_INVALID_EXTENSIONS + ret );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_EXTENSIONS, ret ) );
 
     if( *p != end )
-        return( MBEDTLS_ERR_X509_INVALID_EXTENSIONS +
-                MBEDTLS_ERR_ASN1_LENGTH_MISMATCH );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_EXTENSIONS,
+                MBEDTLS_ERR_ASN1_LENGTH_MISMATCH ) );
 
     /* Do not accept max_pathlen equal to INT_MAX to avoid a signed integer
      * overflow, which is an undefined behavior. */
     if( *max_pathlen == INT_MAX )
-        return( MBEDTLS_ERR_X509_INVALID_EXTENSIONS +
-                MBEDTLS_ERR_ASN1_INVALID_LENGTH );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_EXTENSIONS,
+                MBEDTLS_ERR_ASN1_INVALID_LENGTH ) );
 
     (*max_pathlen)++;
 
@@ -533,11 +533,11 @@
     mbedtls_x509_bitstring bs = { 0, 0, NULL };
 
     if( ( ret = mbedtls_asn1_get_bitstring( p, end, &bs ) ) != 0 )
-        return( MBEDTLS_ERR_X509_INVALID_EXTENSIONS + ret );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_EXTENSIONS, ret ) );
 
     if( bs.len != 1 )
-        return( MBEDTLS_ERR_X509_INVALID_EXTENSIONS +
-                MBEDTLS_ERR_ASN1_INVALID_LENGTH );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_EXTENSIONS,
+                MBEDTLS_ERR_ASN1_INVALID_LENGTH ) );
 
     /* Get actual bitstring */
     *ns_cert_type = *bs.p;
@@ -553,11 +553,11 @@
     mbedtls_x509_bitstring bs = { 0, 0, NULL };
 
     if( ( ret = mbedtls_asn1_get_bitstring( p, end, &bs ) ) != 0 )
-        return( MBEDTLS_ERR_X509_INVALID_EXTENSIONS + ret );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_EXTENSIONS, ret ) );
 
     if( bs.len < 1 )
-        return( MBEDTLS_ERR_X509_INVALID_EXTENSIONS +
-                MBEDTLS_ERR_ASN1_INVALID_LENGTH );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_EXTENSIONS,
+                MBEDTLS_ERR_ASN1_INVALID_LENGTH ) );
 
     /* Get actual bitstring */
     *key_usage = 0;
@@ -581,12 +581,12 @@
     int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
 
     if( ( ret = mbedtls_asn1_get_sequence_of( p, end, ext_key_usage, MBEDTLS_ASN1_OID ) ) != 0 )
-        return( MBEDTLS_ERR_X509_INVALID_EXTENSIONS + ret );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_EXTENSIONS, ret ) );
 
     /* Sequence length must be >= 1 */
     if( ext_key_usage->buf.p == NULL )
-        return( MBEDTLS_ERR_X509_INVALID_EXTENSIONS +
-                MBEDTLS_ERR_ASN1_INVALID_LENGTH );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_EXTENSIONS,
+                MBEDTLS_ERR_ASN1_INVALID_LENGTH ) );
 
     return( 0 );
 }
@@ -631,11 +631,11 @@
     /* Get main sequence tag */
     if( ( ret = mbedtls_asn1_get_tag( p, end, &len,
             MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE ) ) != 0 )
-        return( MBEDTLS_ERR_X509_INVALID_EXTENSIONS + ret );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_EXTENSIONS, ret ) );
 
     if( *p + len != end )
-        return( MBEDTLS_ERR_X509_INVALID_EXTENSIONS +
-                MBEDTLS_ERR_ASN1_LENGTH_MISMATCH );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_EXTENSIONS,
+                MBEDTLS_ERR_ASN1_LENGTH_MISMATCH ) );
 
     while( *p < end )
     {
@@ -645,13 +645,13 @@
         tag = **p;
         (*p)++;
         if( ( ret = mbedtls_asn1_get_len( p, end, &tag_len ) ) != 0 )
-            return( MBEDTLS_ERR_X509_INVALID_EXTENSIONS + ret );
+            return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_EXTENSIONS, ret ) );
 
         if( ( tag & MBEDTLS_ASN1_TAG_CLASS_MASK ) !=
                 MBEDTLS_ASN1_CONTEXT_SPECIFIC )
         {
-            return( MBEDTLS_ERR_X509_INVALID_EXTENSIONS +
-                    MBEDTLS_ERR_ASN1_UNEXPECTED_TAG );
+            return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_EXTENSIONS,
+                    MBEDTLS_ERR_ASN1_UNEXPECTED_TAG ) );
         }
 
         /*
@@ -687,8 +687,8 @@
             cur->next = mbedtls_calloc( 1, sizeof( mbedtls_asn1_sequence ) );
 
             if( cur->next == NULL )
-                return( MBEDTLS_ERR_X509_INVALID_EXTENSIONS +
-                        MBEDTLS_ERR_ASN1_ALLOC_FAILED );
+                return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_EXTENSIONS,
+                        MBEDTLS_ERR_ASN1_ALLOC_FAILED ) );
 
             cur = cur->next;
         }
@@ -704,8 +704,8 @@
     cur->next = NULL;
 
     if( *p != end )
-        return( MBEDTLS_ERR_X509_INVALID_EXTENSIONS +
-                MBEDTLS_ERR_ASN1_LENGTH_MISMATCH );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_EXTENSIONS,
+                MBEDTLS_ERR_ASN1_LENGTH_MISMATCH ) );
 
     return( 0 );
 }
@@ -772,18 +772,18 @@
     ret = mbedtls_asn1_get_tag( p, end, &len,
                              MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE );
     if( ret != 0 )
-        return( MBEDTLS_ERR_X509_INVALID_EXTENSIONS + ret );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_EXTENSIONS, ret ) );
 
     if( *p + len != end )
-        return( MBEDTLS_ERR_X509_INVALID_EXTENSIONS +
-                MBEDTLS_ERR_ASN1_LENGTH_MISMATCH );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_EXTENSIONS,
+                MBEDTLS_ERR_ASN1_LENGTH_MISMATCH ) );
 
     /*
      * Cannot be an empty sequence.
      */
     if( len == 0 )
-        return( MBEDTLS_ERR_X509_INVALID_EXTENSIONS +
-                MBEDTLS_ERR_ASN1_LENGTH_MISMATCH );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_EXTENSIONS,
+                MBEDTLS_ERR_ASN1_LENGTH_MISMATCH ) );
 
     while( *p < end )
     {
@@ -795,13 +795,13 @@
          */
         if( ( ret = mbedtls_asn1_get_tag( p, end, &len,
                 MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE ) ) != 0 )
-            return( MBEDTLS_ERR_X509_INVALID_EXTENSIONS + ret );
+            return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_EXTENSIONS, ret ) );
 
         policy_end = *p + len;
 
         if( ( ret = mbedtls_asn1_get_tag( p, policy_end, &len,
                                           MBEDTLS_ASN1_OID ) ) != 0 )
-            return( MBEDTLS_ERR_X509_INVALID_EXTENSIONS + ret );
+            return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_EXTENSIONS, ret ) );
 
         policy_oid.tag = MBEDTLS_ASN1_OID;
         policy_oid.len = len;
@@ -829,8 +829,8 @@
             cur->next = mbedtls_calloc( 1, sizeof( mbedtls_asn1_sequence ) );
 
             if( cur->next == NULL )
-                return( MBEDTLS_ERR_X509_INVALID_EXTENSIONS +
-                        MBEDTLS_ERR_ASN1_ALLOC_FAILED );
+                return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_EXTENSIONS,
+                        MBEDTLS_ERR_ASN1_ALLOC_FAILED ) );
 
             cur = cur->next;
         }
@@ -850,7 +850,7 @@
         {
             if( ( ret = mbedtls_asn1_get_tag( p, policy_end, &len,
                      MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE ) ) != 0 )
-                return( MBEDTLS_ERR_X509_INVALID_EXTENSIONS + ret );
+                return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_EXTENSIONS, ret ) );
             /*
              * Skip the optional policy qualifiers.
              */
@@ -858,16 +858,16 @@
         }
 
         if( *p != policy_end )
-            return( MBEDTLS_ERR_X509_INVALID_EXTENSIONS +
-                    MBEDTLS_ERR_ASN1_LENGTH_MISMATCH );
+            return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_EXTENSIONS,
+                    MBEDTLS_ERR_ASN1_LENGTH_MISMATCH ) );
     }
 
     /* Set final sequence entry's next pointer to NULL */
     cur->next = NULL;
 
     if( *p != end )
-        return( MBEDTLS_ERR_X509_INVALID_EXTENSIONS +
-                MBEDTLS_ERR_ASN1_LENGTH_MISMATCH );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_EXTENSIONS,
+                MBEDTLS_ERR_ASN1_LENGTH_MISMATCH ) );
 
     return( parse_ret );
 }
@@ -907,14 +907,14 @@
 
         if( ( ret = mbedtls_asn1_get_tag( p, end, &len,
                 MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE ) ) != 0 )
-            return( MBEDTLS_ERR_X509_INVALID_EXTENSIONS + ret );
+            return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_EXTENSIONS, ret ) );
 
         end_ext_data = *p + len;
 
         /* Get extension ID */
         if( ( ret = mbedtls_asn1_get_tag( p, end_ext_data, &extn_oid.len,
                                           MBEDTLS_ASN1_OID ) ) != 0 )
-            return( MBEDTLS_ERR_X509_INVALID_EXTENSIONS + ret );
+            return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_EXTENSIONS, ret ) );
 
         extn_oid.tag = MBEDTLS_ASN1_OID;
         extn_oid.p = *p;
@@ -923,19 +923,19 @@
         /* Get optional critical */
         if( ( ret = mbedtls_asn1_get_bool( p, end_ext_data, &is_critical ) ) != 0 &&
             ( ret != MBEDTLS_ERR_ASN1_UNEXPECTED_TAG ) )
-            return( MBEDTLS_ERR_X509_INVALID_EXTENSIONS + ret );
+            return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_EXTENSIONS, ret ) );
 
         /* Data should be octet string type */
         if( ( ret = mbedtls_asn1_get_tag( p, end_ext_data, &len,
                 MBEDTLS_ASN1_OCTET_STRING ) ) != 0 )
-            return( MBEDTLS_ERR_X509_INVALID_EXTENSIONS + ret );
+            return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_EXTENSIONS, ret ) );
 
         start_ext_octet = *p;
         end_ext_octet = *p + len;
 
         if( end_ext_octet != end_ext_data )
-            return( MBEDTLS_ERR_X509_INVALID_EXTENSIONS +
-                    MBEDTLS_ERR_ASN1_LENGTH_MISMATCH );
+            return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_EXTENSIONS,
+                    MBEDTLS_ERR_ASN1_LENGTH_MISMATCH ) );
 
         /*
          * Detect supported extensions
@@ -961,8 +961,8 @@
             if( is_critical )
             {
                 /* Data is marked as critical: fail */
-                return( MBEDTLS_ERR_X509_INVALID_EXTENSIONS +
-                        MBEDTLS_ERR_ASN1_UNEXPECTED_TAG );
+                return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_EXTENSIONS,
+                        MBEDTLS_ERR_ASN1_UNEXPECTED_TAG ) );
             }
 #endif
             continue;
@@ -1055,8 +1055,8 @@
     }
 
     if( *p != end )
-        return( MBEDTLS_ERR_X509_INVALID_EXTENSIONS +
-                MBEDTLS_ERR_ASN1_LENGTH_MISMATCH );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_EXTENSIONS,
+                MBEDTLS_ERR_ASN1_LENGTH_MISMATCH ) );
 
     return( 0 );
 }
@@ -1134,7 +1134,7 @@
             MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE ) ) != 0 )
     {
         mbedtls_x509_crt_free( crt );
-        return( MBEDTLS_ERR_X509_INVALID_FORMAT + ret );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_FORMAT, ret ) );
     }
 
     end = p + len;
@@ -1181,7 +1181,7 @@
             MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE ) ) != 0 )
     {
         mbedtls_x509_crt_free( crt );
-        return( MBEDTLS_ERR_X509_INVALID_FORMAT + ret );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_FORMAT, ret ) );
     }
 
     if( ( ret = mbedtls_x509_get_name( &p, p + len, &crt->issuer ) ) != 0 )
@@ -1214,7 +1214,7 @@
             MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE ) ) != 0 )
     {
         mbedtls_x509_crt_free( crt );
-        return( MBEDTLS_ERR_X509_INVALID_FORMAT + ret );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_FORMAT, ret ) );
     }
 
     if( len && ( ret = mbedtls_x509_get_name( &p, p + len, &crt->subject ) ) != 0 )
@@ -1279,8 +1279,8 @@
     if( p != end )
     {
         mbedtls_x509_crt_free( crt );
-        return( MBEDTLS_ERR_X509_INVALID_FORMAT +
-                MBEDTLS_ERR_ASN1_LENGTH_MISMATCH );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_FORMAT,
+                MBEDTLS_ERR_ASN1_LENGTH_MISMATCH ) );
     }
 
     end = crt_end;
@@ -1318,8 +1318,8 @@
     if( p != end )
     {
         mbedtls_x509_crt_free( crt );
-        return( MBEDTLS_ERR_X509_INVALID_FORMAT +
-                MBEDTLS_ERR_ASN1_LENGTH_MISMATCH );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_FORMAT,
+                MBEDTLS_ERR_ASN1_LENGTH_MISMATCH ) );
     }
 
     return( 0 );
@@ -1702,7 +1702,7 @@
 
     if( ( ret = mbedtls_asn1_get_tag( &p, end, &len,
                                       MBEDTLS_ASN1_OID ) ) != 0 )
-        return( MBEDTLS_ERR_X509_INVALID_EXTENSIONS + ret );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_EXTENSIONS, ret ) );
 
     cur_oid.tag = MBEDTLS_ASN1_OID;
     cur_oid.p = p;
@@ -1719,20 +1719,20 @@
     if( p + len >= end )
     {
         mbedtls_platform_zeroize( other_name, sizeof( *other_name ) );
-        return( MBEDTLS_ERR_X509_INVALID_EXTENSIONS +
-                MBEDTLS_ERR_ASN1_LENGTH_MISMATCH );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_EXTENSIONS,
+                MBEDTLS_ERR_ASN1_LENGTH_MISMATCH ) );
     }
     p += len;
     if( ( ret = mbedtls_asn1_get_tag( &p, end, &len,
             MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_CONTEXT_SPECIFIC ) ) != 0 )
-        return( MBEDTLS_ERR_X509_INVALID_EXTENSIONS + ret );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_EXTENSIONS, ret ) );
 
     if( ( ret = mbedtls_asn1_get_tag( &p, end, &len,
                      MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE ) ) != 0 )
-       return( MBEDTLS_ERR_X509_INVALID_EXTENSIONS + ret );
+       return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_EXTENSIONS, ret ) );
 
     if( ( ret = mbedtls_asn1_get_tag( &p, end, &len, MBEDTLS_ASN1_OID ) ) != 0 )
-        return( MBEDTLS_ERR_X509_INVALID_EXTENSIONS + ret );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_EXTENSIONS, ret ) );
 
     other_name->value.hardware_module_name.oid.tag = MBEDTLS_ASN1_OID;
     other_name->value.hardware_module_name.oid.p = p;
@@ -1741,13 +1741,13 @@
     if( p + len >= end )
     {
         mbedtls_platform_zeroize( other_name, sizeof( *other_name ) );
-        return( MBEDTLS_ERR_X509_INVALID_EXTENSIONS +
-                MBEDTLS_ERR_ASN1_LENGTH_MISMATCH );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_EXTENSIONS,
+                MBEDTLS_ERR_ASN1_LENGTH_MISMATCH ) );
     }
     p += len;
     if( ( ret = mbedtls_asn1_get_tag( &p, end, &len,
                                       MBEDTLS_ASN1_OCTET_STRING ) ) != 0 )
-        return( MBEDTLS_ERR_X509_INVALID_EXTENSIONS + ret );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_EXTENSIONS, ret ) );
 
     other_name->value.hardware_module_name.val.tag = MBEDTLS_ASN1_OCTET_STRING;
     other_name->value.hardware_module_name.val.p = p;
@@ -1757,8 +1757,8 @@
     {
         mbedtls_platform_zeroize( other_name,
                                   sizeof( *other_name ) );
-        return( MBEDTLS_ERR_X509_INVALID_EXTENSIONS +
-                MBEDTLS_ERR_ASN1_LENGTH_MISMATCH );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_EXTENSIONS,
+                MBEDTLS_ERR_ASN1_LENGTH_MISMATCH ) );
     }
     return( 0 );
 }
diff --git a/library/x509_csr.c b/library/x509_csr.c
index b78c042..25069b2 100644
--- a/library/x509_csr.c
+++ b/library/x509_csr.c
@@ -73,7 +73,7 @@
             return( 0 );
         }
 
-        return( MBEDTLS_ERR_X509_INVALID_VERSION + ret );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_VERSION, ret ) );
     }
 
     return( 0 );
@@ -131,8 +131,8 @@
     if( len != (size_t) ( end - p ) )
     {
         mbedtls_x509_csr_free( csr );
-        return( MBEDTLS_ERR_X509_INVALID_FORMAT +
-                MBEDTLS_ERR_ASN1_LENGTH_MISMATCH );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_FORMAT,
+                MBEDTLS_ERR_ASN1_LENGTH_MISMATCH ) );
     }
 
     /*
@@ -144,7 +144,7 @@
             MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE ) ) != 0 )
     {
         mbedtls_x509_csr_free( csr );
-        return( MBEDTLS_ERR_X509_INVALID_FORMAT + ret );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_FORMAT, ret ) );
     }
 
     end = p + len;
@@ -176,7 +176,7 @@
             MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE ) ) != 0 )
     {
         mbedtls_x509_csr_free( csr );
-        return( MBEDTLS_ERR_X509_INVALID_FORMAT + ret );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_FORMAT, ret ) );
     }
 
     if( ( ret = mbedtls_x509_get_name( &p, p + len, &csr->subject ) ) != 0 )
@@ -210,7 +210,7 @@
             MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_CONTEXT_SPECIFIC ) ) != 0 )
     {
         mbedtls_x509_csr_free( csr );
-        return( MBEDTLS_ERR_X509_INVALID_FORMAT + ret );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_FORMAT, ret ) );
     }
 
     p += len;
@@ -244,8 +244,8 @@
     if( p != end )
     {
         mbedtls_x509_csr_free( csr );
-        return( MBEDTLS_ERR_X509_INVALID_FORMAT +
-                MBEDTLS_ERR_ASN1_LENGTH_MISMATCH );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_FORMAT,
+                MBEDTLS_ERR_ASN1_LENGTH_MISMATCH ) );
     }
 
     return( 0 );
diff --git a/programs/psa/key_ladder_demo.c b/programs/psa/key_ladder_demo.c
index 47d5de6..5d64349 100644
--- a/programs/psa/key_ladder_demo.c
+++ b/programs/psa/key_ladder_demo.c
@@ -365,6 +365,8 @@
     psa_status_t status;
     FILE *input_file = NULL;
     FILE *output_file = NULL;
+    psa_key_attributes_t attributes = PSA_KEY_ATTRIBUTES_INIT;
+    psa_key_type_t key_type;
     long input_position;
     size_t input_size;
     size_t buffer_size = 0;
@@ -385,7 +387,10 @@
     }
 #endif
     input_size = input_position;
-    buffer_size = PSA_AEAD_ENCRYPT_OUTPUT_SIZE( WRAPPING_ALG, input_size );
+    PSA_CHECK( psa_get_key_attributes( wrapping_key, &attributes ) );
+    key_type = psa_get_key_type( &attributes );
+    buffer_size =
+        PSA_AEAD_ENCRYPT_OUTPUT_SIZE( key_type, WRAPPING_ALG, input_size );
     /* Check for integer overflow. */
     if( buffer_size < input_size )
     {
@@ -442,6 +447,8 @@
     psa_status_t status;
     FILE *input_file = NULL;
     FILE *output_file = NULL;
+    psa_key_attributes_t attributes = PSA_KEY_ATTRIBUTES_INIT;
+    psa_key_type_t key_type;
     unsigned char *buffer = NULL;
     size_t ciphertext_size = 0;
     size_t plaintext_size;
@@ -465,8 +472,10 @@
         status = DEMO_ERROR;
         goto exit;
     }
+    PSA_CHECK( psa_get_key_attributes( wrapping_key, &attributes) );
+    key_type = psa_get_key_type( &attributes);
     ciphertext_size =
-        PSA_AEAD_ENCRYPT_OUTPUT_SIZE( WRAPPING_ALG, header.payload_size );
+        PSA_AEAD_ENCRYPT_OUTPUT_SIZE( key_type, WRAPPING_ALG, header.payload_size );
     /* Check for integer overflow. */
     if( ciphertext_size < header.payload_size )
     {
diff --git a/programs/psa/psa_constant_names_generated.c b/programs/psa/psa_constant_names_generated.c
index 2175af9..dcbe87f 100644
--- a/programs/psa/psa_constant_names_generated.c
+++ b/programs/psa/psa_constant_names_generated.c
@@ -169,11 +169,11 @@
         } else if (alg & PSA_ALG_AEAD_AT_LEAST_THIS_LENGTH_FLAG) {
             append(&buffer, buffer_size, &required_size,
                    "PSA_ALG_AEAD_WITH_AT_LEAST_THIS_LENGTH_TAG(", 43);
-            length_modifier = PSA_AEAD_TAG_LENGTH(alg);
+            length_modifier = PSA_ALG_AEAD_GET_TAG_LENGTH(alg);
         } else if (core_alg != alg) {
             append(&buffer, buffer_size, &required_size,
                    "PSA_ALG_AEAD_WITH_SHORTENED_TAG(", 32);
-            length_modifier = PSA_AEAD_TAG_LENGTH(alg);
+            length_modifier = PSA_ALG_AEAD_GET_TAG_LENGTH(alg);
         }
     } else if (PSA_ALG_IS_KEY_AGREEMENT(alg) &&
                !PSA_ALG_IS_RAW_KEY_AGREEMENT(alg)) {
diff --git a/scripts/data_files/error.fmt b/scripts/data_files/error.fmt
index 9e479bb..3be94bd 100644
--- a/scripts/data_files/error.fmt
+++ b/scripts/data_files/error.fmt
@@ -162,4 +162,8 @@
 
 #endif /* MBEDTLS_ERROR_C */
 
+#if defined(MBEDTLS_TEST_HOOKS)
+void (*mbedtls_test_hook_error_add)( int, int, const char *, int );
+#endif
+
 #endif /* MBEDTLS_ERROR_C || MBEDTLS_ERROR_STRERROR_DUMMY */
diff --git a/scripts/generate_psa_constants.py b/scripts/generate_psa_constants.py
index ff07ecd..71afd02 100755
--- a/scripts/generate_psa_constants.py
+++ b/scripts/generate_psa_constants.py
@@ -117,11 +117,11 @@
         } else if (alg & PSA_ALG_AEAD_AT_LEAST_THIS_LENGTH_FLAG) {
             append(&buffer, buffer_size, &required_size,
                    "PSA_ALG_AEAD_WITH_AT_LEAST_THIS_LENGTH_TAG(", 43);
-            length_modifier = PSA_AEAD_TAG_LENGTH(alg);
+            length_modifier = PSA_ALG_AEAD_GET_TAG_LENGTH(alg);
         } else if (core_alg != alg) {
             append(&buffer, buffer_size, &required_size,
                    "PSA_ALG_AEAD_WITH_SHORTENED_TAG(", 32);
-            length_modifier = PSA_AEAD_TAG_LENGTH(alg);
+            length_modifier = PSA_ALG_AEAD_GET_TAG_LENGTH(alg);
         }
     } else if (PSA_ALG_IS_KEY_AGREEMENT(alg) &&
                !PSA_ALG_IS_RAW_KEY_AGREEMENT(alg)) {
diff --git a/tests/include/test/helpers.h b/tests/include/test/helpers.h
index c3a844b..9bfe085 100644
--- a/tests/include/test/helpers.h
+++ b/tests/include/test/helpers.h
@@ -278,4 +278,20 @@
 void mbedtls_test_mutex_usage_check( void );
 #endif /* MBEDTLS_TEST_MUTEX_USAGE */
 
+#if defined(MBEDTLS_TEST_HOOKS)
+/**
+ * \brief   Check that only a pure high-level error code is being combined with
+ *          a pure low-level error code as otherwise the resultant error code
+ *          would be corrupted.
+ *
+ * \note    Both high-level and low-level error codes cannot be greater than
+ *          zero however can be zero. If one error code is zero then the
+ *          other error code is returned even if both codes are zero.
+ *
+ * \note    If the check fails, fail the test currently being run.
+ */
+void mbedtls_test_err_add_check( int high, int low,
+                                 const char *file, int line);
+#endif
+
 #endif /* TEST_HELPERS_H */
diff --git a/tests/src/helpers.c b/tests/src/helpers.c
index e323275..b7c9867 100644
--- a/tests/src/helpers.c
+++ b/tests/src/helpers.c
@@ -282,3 +282,59 @@
     }
 }
 #endif /* MBEDTLS_CHECK_PARAMS */
+
+#if defined(MBEDTLS_TEST_HOOKS)
+void mbedtls_test_err_add_check( int high, int low,
+                                 const char *file, int line )
+{
+    /* Error codes are always negative (a value of zero is a success) however
+     * their positive opposites can be easier to understand. The following
+     * examples given in comments have been made positive for ease of
+     * understanding. The structure of an error code is such:
+     *
+     *                                                shhhhhhhhlllllll
+     *
+     * s = sign bit.
+     * h = high level error code (includes high level module ID (bits 12..14)
+     *     and module-dependent error code (bits 7..11)).
+     * l = low level error code.
+     */
+    if ( high > -0x1000 && high != 0 )
+    /* high < 0001000000000000
+     * No high level module ID bits are set.
+     */
+    {
+        mbedtls_test_fail( "'high' is not a high-level error code",
+                            line, file );
+    }
+    else if ( high < -0x7F80 )
+    /* high > 0111111110000000
+     * Error code is greater than the largest allowed high level module ID.
+     */
+    {
+        mbedtls_test_fail( "'high' error code is greater than 15 bits",
+                            line, file );
+    }
+    else if ( ( high & 0x7F ) != 0 )
+    /* high & 0000000001111111
+     * Error code contains low level error code bits.
+     */
+    {
+        mbedtls_test_fail( "'high' contains a low-level error code",
+                            line, file );
+    }
+    else if ( low < -0x007F )
+    /* low >  0000000001111111
+     * Error code contains high or module level error code bits.
+     */
+    {
+        mbedtls_test_fail( "'low' error code is greater than 7 bits",
+                            line, file );
+    }
+    else if ( low > 0 )
+    {
+        mbedtls_test_fail( "'low' error code is greater than zero",
+                            line, file );
+    }
+}
+#endif /* MBEDTLS_TEST_HOOKS */
diff --git a/tests/suites/main_test.function b/tests/suites/main_test.function
index 36a7d23..ac00f45 100644
--- a/tests/suites/main_test.function
+++ b/tests/suites/main_test.function
@@ -33,6 +33,10 @@
 #include "psa/crypto.h"
 #endif /* MBEDTLS_USE_PSA_CRYPTO */
 
+#if defined(MBEDTLS_TEST_HOOKS)
+#include "mbedtls/error.h"
+#endif
+
 /* Test code may use deprecated identifiers only if the preprocessor symbol
  * MBEDTLS_TEST_DEPRECATED is defined. When building tests, set
  * MBEDTLS_TEST_DEPRECATED explicitly if MBEDTLS_DEPRECATED_WARNING is
@@ -279,6 +283,10 @@
  */
 int main( int argc, const char *argv[] )
 {
+#if defined(MBEDTLS_TEST_HOOKS) && defined (MBEDTLS_ERROR_C)
+    mbedtls_test_hook_error_add = &mbedtls_test_err_add_check;
+#endif
+
     int ret = mbedtls_test_platform_setup();
     if( ret != 0 )
     {
diff --git a/tests/suites/test_suite_psa_crypto.function b/tests/suites/test_suite_psa_crypto.function
index 8f04bc8..bff0c35 100644
--- a/tests/suites/test_suite_psa_crypto.function
+++ b/tests/suites/test_suite_psa_crypto.function
@@ -2924,24 +2924,16 @@
     mbedtls_svc_key_id_t key = MBEDTLS_SVC_KEY_ID_INIT;
     psa_key_type_t key_type = key_type_arg;
     psa_algorithm_t alg = alg_arg;
+    size_t key_bits;
     unsigned char *output_data = NULL;
     size_t output_size = 0;
     size_t output_length = 0;
     unsigned char *output_data2 = NULL;
     size_t output_length2 = 0;
-    size_t tag_length = PSA_AEAD_TAG_LENGTH( alg );
     psa_status_t status = PSA_ERROR_GENERIC_ERROR;
     psa_status_t expected_result = expected_result_arg;
     psa_key_attributes_t attributes = PSA_KEY_ATTRIBUTES_INIT;
 
-    output_size = input_data->len + tag_length;
-    /* For all currently defined algorithms, PSA_AEAD_ENCRYPT_OUTPUT_SIZE
-     * should be exact. */
-    if( expected_result != PSA_ERROR_INVALID_ARGUMENT )
-        TEST_EQUAL( output_size,
-                    PSA_AEAD_ENCRYPT_OUTPUT_SIZE( alg, input_data->len ) );
-    ASSERT_ALLOC( output_data, output_size );
-
     PSA_ASSERT( psa_crypto_init( ) );
 
     psa_set_key_usage_flags( &attributes, PSA_KEY_USAGE_ENCRYPT | PSA_KEY_USAGE_DECRYPT );
@@ -2950,6 +2942,22 @@
 
     PSA_ASSERT( psa_import_key( &attributes, key_data->x, key_data->len,
                                 &key ) );
+    PSA_ASSERT( psa_get_key_attributes( key, &attributes ) );
+    key_bits = psa_get_key_bits( &attributes );
+
+    output_size = input_data->len + PSA_AEAD_TAG_LENGTH( key_type, key_bits,
+                                                         alg );
+    /* For all currently defined algorithms, PSA_AEAD_ENCRYPT_OUTPUT_SIZE
+     * should be exact. */
+    if( expected_result != PSA_ERROR_INVALID_ARGUMENT &&
+        expected_result != PSA_ERROR_NOT_SUPPORTED )
+    {
+        TEST_EQUAL( output_size,
+                    PSA_AEAD_ENCRYPT_OUTPUT_SIZE( key_type, alg, input_data->len ) );
+        TEST_ASSERT( output_size <=
+                     PSA_AEAD_ENCRYPT_OUTPUT_MAX_SIZE( input_data->len ) );
+    }
+    ASSERT_ALLOC( output_data, output_size );
 
     status = psa_aead_encrypt( key, alg,
                                nonce->x, nonce->len,
@@ -2977,7 +2985,7 @@
         /* For all currently defined algorithms, PSA_AEAD_DECRYPT_OUTPUT_SIZE
          * should be exact. */
         TEST_EQUAL( input_data->len,
-                    PSA_AEAD_DECRYPT_OUTPUT_SIZE( alg, output_length ) );
+                    PSA_AEAD_DECRYPT_OUTPUT_SIZE( key_type, alg, output_length ) );
 
         TEST_ASSERT( input_data->len <=
                      PSA_AEAD_DECRYPT_OUTPUT_MAX_SIZE( output_length ) );
@@ -3014,22 +3022,13 @@
     mbedtls_svc_key_id_t key = MBEDTLS_SVC_KEY_ID_INIT;
     psa_key_type_t key_type = key_type_arg;
     psa_algorithm_t alg = alg_arg;
+    size_t key_bits;
     unsigned char *output_data = NULL;
     size_t output_size = 0;
     size_t output_length = 0;
-    size_t tag_length = PSA_AEAD_TAG_LENGTH( alg );
     psa_key_attributes_t attributes = PSA_KEY_ATTRIBUTES_INIT;
     psa_status_t status = PSA_ERROR_GENERIC_ERROR;
 
-    output_size = input_data->len + tag_length;
-    /* For all currently defined algorithms, PSA_AEAD_ENCRYPT_OUTPUT_SIZE
-     * should be exact. */
-    TEST_EQUAL( output_size,
-                PSA_AEAD_ENCRYPT_OUTPUT_SIZE( alg, input_data->len ) );
-    TEST_ASSERT( output_size <=
-                 PSA_AEAD_ENCRYPT_OUTPUT_MAX_SIZE( input_data->len ) );
-    ASSERT_ALLOC( output_data, output_size );
-
     PSA_ASSERT( psa_crypto_init( ) );
 
     psa_set_key_usage_flags( &attributes, PSA_KEY_USAGE_ENCRYPT  );
@@ -3038,6 +3037,18 @@
 
     PSA_ASSERT( psa_import_key( &attributes, key_data->x, key_data->len,
                                 &key ) );
+    PSA_ASSERT( psa_get_key_attributes( key, &attributes ) );
+    key_bits = psa_get_key_bits( &attributes );
+
+    output_size = input_data->len + PSA_AEAD_TAG_LENGTH( key_type, key_bits,
+                                                         alg );
+    /* For all currently defined algorithms, PSA_AEAD_ENCRYPT_OUTPUT_SIZE
+     * should be exact. */
+    TEST_EQUAL( output_size,
+                PSA_AEAD_ENCRYPT_OUTPUT_SIZE( key_type, alg, input_data->len ) );
+    TEST_ASSERT( output_size <=
+                 PSA_AEAD_ENCRYPT_OUTPUT_MAX_SIZE( input_data->len ) );
+    ASSERT_ALLOC( output_data, output_size );
 
     status = psa_aead_encrypt( key, alg,
                                nonce->x, nonce->len,
@@ -3078,26 +3089,14 @@
     mbedtls_svc_key_id_t key = MBEDTLS_SVC_KEY_ID_INIT;
     psa_key_type_t key_type = key_type_arg;
     psa_algorithm_t alg = alg_arg;
+    size_t key_bits;
     unsigned char *output_data = NULL;
     size_t output_size = 0;
     size_t output_length = 0;
-    size_t tag_length = PSA_AEAD_TAG_LENGTH( alg );
     psa_key_attributes_t attributes = PSA_KEY_ATTRIBUTES_INIT;
     psa_status_t expected_result = expected_result_arg;
     psa_status_t status = PSA_ERROR_GENERIC_ERROR;
 
-    output_size = input_data->len - tag_length;
-    if( expected_result != PSA_ERROR_INVALID_ARGUMENT )
-    {
-        /* For all currently defined algorithms, PSA_AEAD_DECRYPT_OUTPUT_SIZE
-         * should be exact. */
-        TEST_EQUAL( output_size,
-                    PSA_AEAD_DECRYPT_OUTPUT_SIZE( alg, input_data->len ) );
-        TEST_ASSERT( output_size <=
-                     PSA_AEAD_DECRYPT_OUTPUT_MAX_SIZE( input_data->len ) );
-    }
-    ASSERT_ALLOC( output_data, output_size );
-
     PSA_ASSERT( psa_crypto_init( ) );
 
     psa_set_key_usage_flags( &attributes, PSA_KEY_USAGE_DECRYPT  );
@@ -3106,6 +3105,22 @@
 
     PSA_ASSERT( psa_import_key( &attributes, key_data->x, key_data->len,
                                 &key ) );
+    PSA_ASSERT( psa_get_key_attributes( key, &attributes ) );
+    key_bits = psa_get_key_bits( &attributes );
+
+    output_size = input_data->len - PSA_AEAD_TAG_LENGTH( key_type, key_bits,
+                                                         alg );
+    if( expected_result != PSA_ERROR_INVALID_ARGUMENT &&
+        expected_result != PSA_ERROR_NOT_SUPPORTED )
+    {
+        /* For all currently defined algorithms, PSA_AEAD_DECRYPT_OUTPUT_SIZE
+         * should be exact. */
+        TEST_EQUAL( output_size,
+                    PSA_AEAD_DECRYPT_OUTPUT_SIZE( key_type, alg, input_data->len ) );
+        TEST_ASSERT( output_size <=
+                     PSA_AEAD_DECRYPT_OUTPUT_MAX_SIZE( input_data->len ) );
+    }
+    ASSERT_ALLOC( output_data, output_size );
 
     status = psa_aead_decrypt( key, alg,
                                nonce->x, nonce->len,
diff --git a/tests/suites/test_suite_psa_crypto_driver_wrappers.function b/tests/suites/test_suite_psa_crypto_driver_wrappers.function
index 8679a1e..f16d1d5 100644
--- a/tests/suites/test_suite_psa_crypto_driver_wrappers.function
+++ b/tests/suites/test_suite_psa_crypto_driver_wrappers.function
@@ -822,24 +822,15 @@
     mbedtls_svc_key_id_t key = MBEDTLS_SVC_KEY_ID_INIT;
     psa_key_type_t key_type = key_type_arg;
     psa_algorithm_t alg = alg_arg;
+    size_t key_bits;
     psa_status_t forced_status = forced_status_arg;
     unsigned char *output_data = NULL;
     size_t output_size = 0;
     size_t output_length = 0;
-    size_t tag_length = PSA_AEAD_TAG_LENGTH( alg );
     psa_key_attributes_t attributes = PSA_KEY_ATTRIBUTES_INIT;
     psa_status_t status = PSA_ERROR_GENERIC_ERROR;
     test_driver_aead_hooks = test_driver_aead_hooks_init();
 
-    output_size = input_data->len + tag_length;
-    /* For all currently defined algorithms, PSA_AEAD_ENCRYPT_OUTPUT_SIZE
-     * should be exact. */
-    TEST_EQUAL( output_size,
-                PSA_AEAD_ENCRYPT_OUTPUT_SIZE( alg, input_data->len ) );
-    TEST_ASSERT( output_size <=
-                 PSA_AEAD_ENCRYPT_OUTPUT_MAX_SIZE( input_data->len ) );
-    ASSERT_ALLOC( output_data, output_size );
-
     PSA_ASSERT( psa_crypto_init( ) );
 
     psa_set_key_usage_flags( &attributes, PSA_KEY_USAGE_ENCRYPT  );
@@ -848,6 +839,18 @@
 
     PSA_ASSERT( psa_import_key( &attributes, key_data->x, key_data->len,
                                 &key ) );
+    PSA_ASSERT( psa_get_key_attributes( key, &attributes ) );
+    key_bits = psa_get_key_bits( &attributes );
+
+    output_size = input_data->len + PSA_AEAD_TAG_LENGTH( key_type, key_bits,
+                                                         alg );
+    /* For all currently defined algorithms, PSA_AEAD_ENCRYPT_OUTPUT_SIZE
+     * should be exact. */
+    TEST_EQUAL( output_size,
+                PSA_AEAD_ENCRYPT_OUTPUT_SIZE( key_type, alg, input_data->len ) );
+    TEST_ASSERT( output_size <=
+                 PSA_AEAD_ENCRYPT_OUTPUT_MAX_SIZE( input_data->len ) );
+    ASSERT_ALLOC( output_data, output_size );
 
     test_driver_aead_hooks.forced_status = forced_status;
     status = psa_aead_encrypt( key, alg,
@@ -888,18 +891,15 @@
     mbedtls_svc_key_id_t key = MBEDTLS_SVC_KEY_ID_INIT;
     psa_key_type_t key_type = key_type_arg;
     psa_algorithm_t alg = alg_arg;
+    size_t key_bits;
     psa_status_t forced_status = forced_status_arg;
     unsigned char *output_data = NULL;
     size_t output_size = 0;
     size_t output_length = 0;
-    size_t tag_length = PSA_AEAD_TAG_LENGTH( alg );
     psa_key_attributes_t attributes = PSA_KEY_ATTRIBUTES_INIT;
     psa_status_t status = PSA_ERROR_GENERIC_ERROR;
     test_driver_aead_hooks = test_driver_aead_hooks_init();
 
-    output_size = input_data->len - tag_length;
-    ASSERT_ALLOC( output_data, output_size );
-
     PSA_ASSERT( psa_crypto_init( ) );
 
     psa_set_key_usage_flags( &attributes, PSA_KEY_USAGE_DECRYPT  );
@@ -908,6 +908,12 @@
 
     PSA_ASSERT( psa_import_key( &attributes, key_data->x, key_data->len,
                                 &key ) );
+    PSA_ASSERT( psa_get_key_attributes( key, &attributes ) );
+    key_bits = psa_get_key_bits( &attributes );
+
+    output_size = input_data->len - PSA_AEAD_TAG_LENGTH( key_type, key_bits,
+                                                         alg );
+    ASSERT_ALLOC( output_data, output_size );
 
     test_driver_aead_hooks.forced_status = forced_status;
     status = psa_aead_decrypt( key, alg,
diff --git a/tests/suites/test_suite_psa_crypto_metadata.data b/tests/suites/test_suite_psa_crypto_metadata.data
index bd98a76..4e2f4d5 100644
--- a/tests/suites/test_suite_psa_crypto_metadata.data
+++ b/tests/suites/test_suite_psa_crypto_metadata.data
@@ -134,17 +134,57 @@
 depends_on:PSA_WANT_ALG_XTS:MBEDTLS_CIPHER_C
 cipher_algorithm:PSA_ALG_XTS:0
 
-AEAD: CCM
-depends_on:PSA_WANT_ALG_CCM
-aead_algorithm:PSA_ALG_CCM:ALG_IS_AEAD_ON_BLOCK_CIPHER:16
+AEAD: CCM-AES-128
+depends_on:PSA_WANT_KEY_TYPE_AES:PSA_WANT_ALG_CCM
+aead_algorithm:PSA_ALG_CCM:ALG_IS_AEAD_ON_BLOCK_CIPHER:16:PSA_KEY_TYPE_AES:128
 
-AEAD: GCM
-depends_on:PSA_WANT_ALG_GCM
-aead_algorithm:PSA_ALG_GCM:ALG_IS_AEAD_ON_BLOCK_CIPHER:16
+AEAD: CCM-AES-192
+depends_on:PSA_WANT_KEY_TYPE_AES:PSA_WANT_ALG_CCM
+aead_algorithm:PSA_ALG_CCM:ALG_IS_AEAD_ON_BLOCK_CIPHER:16:PSA_KEY_TYPE_AES:192
+
+AEAD: CCM-AES-256
+depends_on:PSA_WANT_KEY_TYPE_AES:PSA_WANT_ALG_CCM
+aead_algorithm:PSA_ALG_CCM:ALG_IS_AEAD_ON_BLOCK_CIPHER:16:PSA_KEY_TYPE_AES:256
+
+AEAD: CCM-CAMELLIA-128
+depends_on:PSA_WANT_KEY_TYPE_CAMELLIA:PSA_WANT_ALG_CCM
+aead_algorithm:PSA_ALG_CCM:ALG_IS_AEAD_ON_BLOCK_CIPHER:16:PSA_KEY_TYPE_CAMELLIA:128
+
+AEAD: CCM-CAMELLIA-192
+depends_on:PSA_WANT_KEY_TYPE_CAMELLIA:PSA_WANT_ALG_CCM
+aead_algorithm:PSA_ALG_CCM:ALG_IS_AEAD_ON_BLOCK_CIPHER:16:PSA_KEY_TYPE_CAMELLIA:192
+
+AEAD: CCM-CAMELLIA-256
+depends_on:PSA_WANT_KEY_TYPE_CAMELLIA:PSA_WANT_ALG_CCM
+aead_algorithm:PSA_ALG_CCM:ALG_IS_AEAD_ON_BLOCK_CIPHER:16:PSA_KEY_TYPE_CAMELLIA:256
+
+AEAD: GCM-AES-128
+depends_on:PSA_WANT_KEY_TYPE_AES:PSA_WANT_ALG_GCM
+aead_algorithm:PSA_ALG_GCM:ALG_IS_AEAD_ON_BLOCK_CIPHER:16:PSA_KEY_TYPE_AES:128
+
+AEAD: GCM-AES-192
+depends_on:PSA_WANT_KEY_TYPE_AES:PSA_WANT_ALG_GCM
+aead_algorithm:PSA_ALG_GCM:ALG_IS_AEAD_ON_BLOCK_CIPHER:16:PSA_KEY_TYPE_AES:192
+
+AEAD: GCM-AES-256
+depends_on:PSA_WANT_KEY_TYPE_AES:PSA_WANT_ALG_GCM
+aead_algorithm:PSA_ALG_GCM:ALG_IS_AEAD_ON_BLOCK_CIPHER:16:PSA_KEY_TYPE_AES:256
+
+AEAD: GCM-CAMELLIA-128
+depends_on:PSA_WANT_KEY_TYPE_CAMELLIA:PSA_WANT_ALG_GCM
+aead_algorithm:PSA_ALG_GCM:ALG_IS_AEAD_ON_BLOCK_CIPHER:16:PSA_KEY_TYPE_CAMELLIA:128
+
+AEAD: GCM-CAMELLIA-192
+depends_on:PSA_WANT_KEY_TYPE_CAMELLIA:PSA_WANT_ALG_GCM
+aead_algorithm:PSA_ALG_GCM:ALG_IS_AEAD_ON_BLOCK_CIPHER:16:PSA_KEY_TYPE_CAMELLIA:192
+
+AEAD: GCM-CAMELLIA-256
+depends_on:PSA_WANT_KEY_TYPE_CAMELLIA:PSA_WANT_ALG_GCM
+aead_algorithm:PSA_ALG_GCM:ALG_IS_AEAD_ON_BLOCK_CIPHER:16:PSA_KEY_TYPE_CAMELLIA:256
 
 AEAD: ChaCha20_Poly1305
 depends_on:PSA_WANT_ALG_CHACHA20_POLY1305
-aead_algorithm:PSA_ALG_CHACHA20_POLY1305:0:16
+aead_algorithm:PSA_ALG_CHACHA20_POLY1305:0:16:PSA_KEY_TYPE_CHACHA20:256
 
 Asymmetric signature: RSA PKCS#1 v1.5 raw
 depends_on:PSA_WANT_ALG_RSA_PKCS1V15_SIGN
diff --git a/tests/suites/test_suite_psa_crypto_metadata.function b/tests/suites/test_suite_psa_crypto_metadata.function
index 8acbe44..8134f44 100644
--- a/tests/suites/test_suite_psa_crypto_metadata.function
+++ b/tests/suites/test_suite_psa_crypto_metadata.function
@@ -169,6 +169,7 @@
 }
 
 void aead_algorithm_core( psa_algorithm_t alg, int classification_flags,
+                          psa_key_type_t key_type, size_t key_bits,
                           size_t tag_length )
 {
     /* Algorithm classification */
@@ -183,7 +184,7 @@
     algorithm_classification( alg, classification_flags );
 
     /* Tag length */
-    TEST_EQUAL( tag_length, PSA_AEAD_TAG_LENGTH( alg ) );
+    TEST_EQUAL( tag_length, PSA_AEAD_TAG_LENGTH( key_type, key_bits, alg ) );
 
 exit: ;
 }
@@ -367,19 +368,24 @@
 
 /* BEGIN_CASE */
 void aead_algorithm( int alg_arg, int classification_flags,
-                     int tag_length_arg )
+                     int tag_length_arg,
+                     int key_type_arg, int key_bits_arg )
 {
     psa_algorithm_t alg = alg_arg;
     size_t tag_length = tag_length_arg;
     size_t n;
+    psa_key_type_t key_type = key_type_arg;
+    size_t key_bits = key_bits_arg;
 
-    aead_algorithm_core( alg, classification_flags, tag_length );
+    aead_algorithm_core( alg, classification_flags,
+                         key_type, key_bits, tag_length );
 
     /* Truncated versions */
     for( n = 1; n <= tag_length; n++ )
     {
         psa_algorithm_t truncated_alg = PSA_ALG_AEAD_WITH_SHORTENED_TAG( alg, n );
-        aead_algorithm_core( truncated_alg, classification_flags, n );
+        aead_algorithm_core( truncated_alg, classification_flags,
+                             key_type, key_bits, n );
         TEST_EQUAL( PSA_ALG_AEAD_WITH_DEFAULT_LENGTH_TAG( truncated_alg ),
                     alg );
         /* Check that calling PSA_ALG_AEAD_WITH_SHORTENED_TAG twice gives
@@ -411,7 +417,8 @@
     for( n = 1; n <= tag_length; n++ )
     {
         psa_algorithm_t policy_alg = PSA_ALG_AEAD_WITH_AT_LEAST_THIS_LENGTH_TAG( alg, n );
-        aead_algorithm_core( policy_alg, classification_flags | ALG_IS_WILDCARD, n );
+        aead_algorithm_core( policy_alg, classification_flags | ALG_IS_WILDCARD,
+                             key_type, key_bits, n );
         TEST_EQUAL( PSA_ALG_AEAD_WITH_DEFAULT_LENGTH_TAG( policy_alg ),
                     alg );
         /* Check that calling PSA_ALG_AEAD_WITH_AT_LEAST_THIS_LENGTH_TAG twice
diff --git a/tests/suites/test_suite_x509parse.function b/tests/suites/test_suite_x509parse.function
index f536488..a6361d8 100644
--- a/tests/suites/test_suite_x509parse.function
+++ b/tests/suites/test_suite_x509parse.function
@@ -7,6 +7,7 @@
 #include "mbedtls/pem.h"
 #include "mbedtls/oid.h"
 #include "mbedtls/base64.h"
+#include "mbedtls/error.h"
 #include "string.h"
 
 #if MBEDTLS_X509_MAX_INTERMEDIATE_CA > 19
@@ -320,18 +321,18 @@
         ret = mbedtls_asn1_get_tag( p, end, &len,
                                  MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE );
         if( ret != 0 )
-            return( MBEDTLS_ERR_X509_INVALID_EXTENSIONS + ret );
+            return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_EXTENSIONS, ret ) );
 
         if( *p + len != end )
-            return( MBEDTLS_ERR_X509_INVALID_EXTENSIONS +
-                    MBEDTLS_ERR_ASN1_LENGTH_MISMATCH );
+            return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_EXTENSIONS,
+                    MBEDTLS_ERR_ASN1_LENGTH_MISMATCH ) );
 
         /*
          * Cannot be an empty sequence.
          */
         if( len == 0 )
-            return( MBEDTLS_ERR_X509_INVALID_EXTENSIONS +
-                    MBEDTLS_ERR_ASN1_LENGTH_MISMATCH );
+            return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_EXTENSIONS,
+                    MBEDTLS_ERR_ASN1_LENGTH_MISMATCH ) );
 
         while( *p < end )
         {
@@ -342,13 +343,13 @@
              */
             if( ( ret = mbedtls_asn1_get_tag( p, end, &len,
                     MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE ) ) != 0 )
-                return( MBEDTLS_ERR_X509_INVALID_EXTENSIONS + ret );
+                return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_EXTENSIONS, ret ) );
 
             policy_end = *p + len;
 
             if( ( ret = mbedtls_asn1_get_tag( p, policy_end, &len,
                                               MBEDTLS_ASN1_OID ) ) != 0 )
-                return( MBEDTLS_ERR_X509_INVALID_EXTENSIONS + ret );
+                return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_EXTENSIONS, ret ) );
 
             /*
              * Recognize exclusively the policy with OID 1
@@ -366,7 +367,7 @@
             {
                 if( ( ret = mbedtls_asn1_get_tag( p, policy_end, &len,
                          MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE ) ) != 0 )
-                    return( MBEDTLS_ERR_X509_INVALID_EXTENSIONS + ret );
+                    return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_EXTENSIONS, ret ) );
                 /*
                  * Skip the optional policy qualifiers.
                  */
@@ -374,13 +375,13 @@
             }
 
             if( *p != policy_end )
-                return( MBEDTLS_ERR_X509_INVALID_EXTENSIONS +
-                        MBEDTLS_ERR_ASN1_LENGTH_MISMATCH );
+                return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_EXTENSIONS,
+                        MBEDTLS_ERR_ASN1_LENGTH_MISMATCH ) );
         }
 
         if( *p != end )
-            return( MBEDTLS_ERR_X509_INVALID_EXTENSIONS +
-                    MBEDTLS_ERR_ASN1_LENGTH_MISMATCH );
+            return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_EXTENSIONS,
+                    MBEDTLS_ERR_ASN1_LENGTH_MISMATCH ) );
 
         return( parse_ret );
     }
@@ -388,7 +389,8 @@
              memcmp( new_oid->p, oid->p, oid->len ) == 0 )
         return( 0 );
     else
-        return( MBEDTLS_ERR_X509_INVALID_EXTENSIONS + MBEDTLS_ERR_ASN1_UNEXPECTED_TAG );
+        return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_EXTENSIONS,
+                                   MBEDTLS_ERR_ASN1_UNEXPECTED_TAG ) );
 }
 #endif /* MBEDTLS_X509_CRT_PARSE_C */
 /* END_HEADER */