diff --git a/include/mbedtls/ccm.h b/include/mbedtls/ccm.h
index dfb1b5e..009231e 100644
--- a/include/mbedtls/ccm.h
+++ b/include/mbedtls/ccm.h
@@ -57,7 +57,6 @@
 /* MBEDTLS_ERR_CCM_HW_ACCEL_FAILED is deprecated and should not be used. */
 #define MBEDTLS_ERR_CCM_HW_ACCEL_FAILED -0x0011 /**< CCM hardware accelerator failed. */
 
-
 #ifdef __cplusplus
 extern "C" {
 #endif
@@ -85,7 +84,7 @@
  *                  to make references valid, and prepare the context
  *                  for mbedtls_ccm_setkey() or mbedtls_ccm_free().
  *
- * \param ctx       The CCM context to initialize.
+ * \param ctx       The CCM context to initialize. Must not be NULL.
  */
 void mbedtls_ccm_init( mbedtls_ccm_context *ctx );
 
@@ -93,9 +92,9 @@
  * \brief           This function initializes the CCM context set in the
  *                  \p ctx parameter and sets the encryption key.
  *
- * \param ctx       The CCM context to initialize.
+ * \param ctx       The CCM context to initialize. Must not be NULL.
  * \param cipher    The 128-bit block cipher to use.
- * \param key       The encryption key.
+ * \param key       The encryption key. Must not be NULL.
  * \param keybits   The key size in bits. This must be acceptable by the cipher.
  *
  * \return          \c 0 on success.
@@ -110,7 +109,7 @@
  * \brief   This function releases and clears the specified CCM context
  *          and underlying cipher sub-context.
  *
- * \param ctx       The CCM context to clear.
+ * \param ctx       The CCM context to clear. Must not be NULL.
  */
 void mbedtls_ccm_free( mbedtls_ccm_context *ctx );
 
@@ -123,19 +122,20 @@
  *                  \p tag = \p output + \p length, and make sure that the
  *                  output buffer is at least \p length + \p tag_len wide.
  *
- * \param ctx       The CCM context to use for encryption.
+ * \param ctx       The CCM context to use for encryption. Must not be NULL.
  * \param length    The length of the input data in Bytes.
- * \param iv        Initialization vector (nonce).
+ * \param iv        Initialization vector (nonce). Must not be NULL.
  * \param iv_len    The length of the nonce in Bytes: 7, 8, 9, 10, 11, 12,
  *                  or 13. The length L of the message length field is
  *                  15 - \p iv_len.
- * \param add       The additional data field.
+ * \param add       The additional data field. Must not be NULL.
  * \param add_len   The length of additional data in Bytes.
  *                  Must be less than 2^16 - 2^8.
- * \param input     The buffer holding the input data.
+ * \param input     The buffer holding the input data. Must not be NULL.
  * \param output    The buffer holding the output data.
  *                  Must be at least \p length Bytes wide.
- * \param tag       The buffer holding the authentication field.
+ * \param tag       The buffer holding the authentication field. Must not be
+ *                  NULL.
  * \param tag_len   The length of the authentication field to generate in Bytes:
  *                  4, 6, 8, 10, 12, 14 or 16.
  *
@@ -161,19 +161,20 @@
  *                  the tag length has to be encoded into the \p iv passed to
  *                  this function.
  *
- * \param ctx       The CCM context to use for encryption.
+ * \param ctx       The CCM context to use for encryption. Must not be NULL.
  * \param length    The length of the input data in Bytes.
- * \param iv        Initialization vector (nonce).
+ * \param iv        Initialization vector (nonce). Must not be NULL.
  * \param iv_len    The length of the nonce in Bytes: 7, 8, 9, 10, 11, 12,
  *                  or 13. The length L of the message length field is
  *                  15 - \p iv_len.
- * \param add       The additional data field.
+ * \param add       The additional data field. Must not be NULL.
  * \param add_len   The length of additional data in Bytes.
  *                  Must be less than 2^16 - 2^8.
- * \param input     The buffer holding the input data.
+ * \param input     The buffer holding the input data. Must not be NULL.
  * \param output    The buffer holding the output data.
  *                  Must be at least \p length Bytes wide.
- * \param tag       The buffer holding the authentication field.
+ * \param tag       The buffer holding the authentication field. Must not be
+ *                  NULL.
  * \param tag_len   The length of the authentication field to generate in Bytes:
  *                  0, 4, 6, 8, 10, 12, 14 or 16.
  *
@@ -193,19 +194,20 @@
  * \brief           This function performs a CCM authenticated decryption of a
  *                  buffer.
  *
- * \param ctx       The CCM context to use for decryption.
+ * \param ctx       The CCM context to use for decryption. Must not be NULL.
  * \param length    The length of the input data in Bytes.
- * \param iv        Initialization vector (nonce).
+ * \param iv        Initialization vector (nonce). Must not be NULL.
  * \param iv_len    The length of the nonce in Bytes: 7, 8, 9, 10, 11, 12,
  *                  or 13. The length L of the message length field is
  *                  15 - \p iv_len.
- * \param add       The additional data field.
+ * \param add       The additional data field. Must not be NULL.
  * \param add_len   The length of additional data in Bytes.
  *                  Must be less than 2^16 - 2^8.
- * \param input     The buffer holding the input data.
+ * \param input     The buffer holding the input data. Must not be NULL.
  * \param output    The buffer holding the output data.
  *                  Must be at least \p length Bytes wide.
- * \param tag       The buffer holding the authentication field.
+ * \param tag       The buffer holding the authentication field. Must not be
+ *                  NULL.
  * \param tag_len   The length of the authentication field in Bytes.
  *                  4, 6, 8, 10, 12, 14 or 16.
  *
@@ -228,19 +230,20 @@
  *                  this function as \p tag_len. (\p tag needs to be adjusted
  *                  accordingly.)
  *
- * \param ctx       The CCM context to use for decryption.
+ * \param ctx       The CCM context to use for decryption. Must not be NULL.
  * \param length    The length of the input data in Bytes.
- * \param iv        Initialization vector (nonce).
+ * \param iv        Initialization vector (nonce). Must not be NULL.
  * \param iv_len    The length of the nonce in Bytes: 7, 8, 9, 10, 11, 12,
  *                  or 13. The length L of the message length field is
  *                  15 - \p iv_len.
- * \param add       The additional data field.
+ * \param add       The additional data field. Must not be NULL.
  * \param add_len   The length of additional data in Bytes.
  *                  Must be less than 2^16 - 2^8.
- * \param input     The buffer holding the input data.
+ * \param input     The buffer holding the input data. Must not be NULL.
  * \param output    The buffer holding the output data.
  *                  Must be at least \p length Bytes wide.
- * \param tag       The buffer holding the authentication field.
+ * \param tag       The buffer holding the authentication field. Must not be
+ *                  NULL.
  * \param tag_len   The length of the authentication field in Bytes.
  *                  0, 4, 6, 8, 10, 12, 14 or 16.
  *