diff --git a/library/ssl_tls.c b/library/ssl_tls.c
index 06c30f6..668b5ec 100644
--- a/library/ssl_tls.c
+++ b/library/ssl_tls.c
@@ -275,6 +275,7 @@
 }
 
 #if defined(MBEDTLS_SSL_VARIABLE_BUFFER_LENGTH)
+MBEDTLS_CHECK_RETURN_CRITICAL
 static int resize_buffer( unsigned char **buffer, size_t len_new, size_t *len_old )
 {
     unsigned char* resized_buffer = mbedtls_calloc( 1, len_new );
@@ -380,6 +381,7 @@
                           const unsigned char *, size_t,
                           unsigned char *, size_t);
 
+MBEDTLS_CHECK_RETURN_CRITICAL
 static int ssl_tls12_populate_transform( mbedtls_ssl_transform *transform,
                                    int ciphersuite,
                                    const unsigned char master[48],
@@ -393,6 +395,7 @@
                                    const mbedtls_ssl_context *ssl );
 
 #if defined(MBEDTLS_SHA256_C)
+MBEDTLS_CHECK_RETURN_CRITICAL
 static int tls_prf_sha256( const unsigned char *secret, size_t slen,
                            const char *label,
                            const unsigned char *random, size_t rlen,
@@ -403,6 +406,7 @@
 #endif /* MBEDTLS_SHA256_C */
 
 #if defined(MBEDTLS_SHA384_C)
+MBEDTLS_CHECK_RETURN_CRITICAL
 static int tls_prf_sha384( const unsigned char *secret, size_t slen,
                            const char *label,
                            const unsigned char *random, size_t rlen,
@@ -415,6 +419,7 @@
 static size_t ssl_session_save_tls12( const mbedtls_ssl_session *session,
                                       unsigned char *buf,
                                       size_t buf_len );
+MBEDTLS_CHECK_RETURN_CRITICAL
 static int ssl_session_load_tls12( mbedtls_ssl_session *session,
                                    const unsigned char *buf,
                                    size_t len );
@@ -672,6 +677,7 @@
     memset( session, 0, sizeof(mbedtls_ssl_session) );
 }
 
+MBEDTLS_CHECK_RETURN_CRITICAL
 static int ssl_handshake_init( mbedtls_ssl_context *ssl )
 {
     /* Clear old handshake information if present */
@@ -863,6 +869,7 @@
 
 #if defined(MBEDTLS_SSL_DTLS_HELLO_VERIFY) && defined(MBEDTLS_SSL_SRV_C)
 /* Dummy cookie callbacks for defaults */
+MBEDTLS_CHECK_RETURN_CRITICAL
 static int ssl_cookie_write_dummy( void *ctx,
                       unsigned char **p, unsigned char *end,
                       const unsigned char *cli_id, size_t cli_id_len )
@@ -876,6 +883,7 @@
     return( MBEDTLS_ERR_SSL_FEATURE_UNAVAILABLE );
 }
 
+MBEDTLS_CHECK_RETURN_CRITICAL
 static int ssl_cookie_check_dummy( void *ctx,
                       const unsigned char *cookie, size_t cookie_len,
                       const unsigned char *cli_id, size_t cli_id_len )
@@ -898,6 +906,7 @@
     memset( ssl, 0, sizeof( mbedtls_ssl_context ) );
 }
 
+MBEDTLS_CHECK_RETURN_CRITICAL
 static int ssl_conf_version_check( const mbedtls_ssl_context *ssl )
 {
     const mbedtls_ssl_config *conf = ssl->conf;
@@ -949,6 +958,7 @@
     return( MBEDTLS_ERR_SSL_BAD_CONFIG );
 }
 
+MBEDTLS_CHECK_RETURN_CRITICAL
 static int ssl_conf_check(const mbedtls_ssl_context *ssl)
 {
     int ret;
@@ -1372,6 +1382,7 @@
 }
 
 /* Append a new keycert entry to a (possibly empty) list */
+MBEDTLS_CHECK_RETURN_CRITICAL
 static int ssl_append_key_cert( mbedtls_ssl_key_cert **head,
                                 mbedtls_x509_crt *cert,
                                 mbedtls_pk_context *key )
@@ -1517,6 +1528,7 @@
 
 #if defined(MBEDTLS_KEY_EXCHANGE_SOME_PSK_ENABLED)
 
+MBEDTLS_CHECK_RETURN_CRITICAL
 static int ssl_conf_psk_is_configured( mbedtls_ssl_config const *conf )
 {
 #if defined(MBEDTLS_USE_PSA_CRYPTO)
@@ -1562,6 +1574,7 @@
  * It checks that the provided identity is well-formed and attempts
  * to make a copy of it in the SSL config.
  * On failure, the PSK identity in the config remains unset. */
+MBEDTLS_CHECK_RETURN_CRITICAL
 static int ssl_conf_set_psk_identity( mbedtls_ssl_config *conf,
                                       unsigned char const *psk_identity,
                                       size_t psk_identity_len )
@@ -2756,6 +2769,7 @@
  *
  */
 
+MBEDTLS_CHECK_RETURN_CRITICAL
 static int ssl_session_save( const mbedtls_ssl_session *session,
                              unsigned char omit_header,
                              unsigned char *buf,
@@ -2830,6 +2844,7 @@
  * This internal version is wrapped by a public function that cleans up in
  * case of error, and has an extra option omit_header.
  */
+MBEDTLS_CHECK_RETURN_CRITICAL
 static int ssl_session_load( mbedtls_ssl_session *session,
                              unsigned char omit_header,
                              const unsigned char *buf,
@@ -2896,6 +2911,7 @@
 /*
  * Perform a single step of the SSL handshake
  */
+MBEDTLS_CHECK_RETURN_CRITICAL
 static int ssl_prepare_handshake_step( mbedtls_ssl_context *ssl )
 {
     int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
@@ -3054,6 +3070,7 @@
 /*
  * Write HelloRequest to request renegotiation on server
  */
+MBEDTLS_CHECK_RETURN_CRITICAL
 static int ssl_write_hello_request( mbedtls_ssl_context *ssl )
 {
     int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
@@ -3652,6 +3669,7 @@
  * This internal version is wrapped by a public function that cleans up in
  * case of error.
  */
+MBEDTLS_CHECK_RETURN_CRITICAL
 static int ssl_context_load( mbedtls_ssl_context *ssl,
                              const unsigned char *buf,
                              size_t len )
@@ -4235,6 +4253,7 @@
 #if defined(MBEDTLS_DEBUG_C) && defined(MBEDTLS_KEY_EXCHANGE_WITH_CERT_ENABLED)
 /* Function for checking `ssl_preset_*_sig_algs` and `ssl_tls12_preset_*_sig_algs`
  * to make sure there are no duplicated signature algorithm entries. */
+MBEDTLS_CHECK_RETURN_CRITICAL
 static int ssl_check_no_sig_alg_duplication( uint16_t * sig_algs )
 {
     size_t i, j;
@@ -4786,6 +4805,7 @@
 #else /* MBEDTLS_USE_PSA_CRYPTO */
 
 #if defined(MBEDTLS_SHA384_C)
+MBEDTLS_CHECK_RETURN_CRITICAL
 static int ssl_get_handshake_transcript_sha384( mbedtls_ssl_context *ssl,
                                                 unsigned char *dst,
                                                 size_t dst_len,
@@ -4816,6 +4836,7 @@
 #endif /* MBEDTLS_SHA384_C */
 
 #if defined(MBEDTLS_SHA256_C)
+MBEDTLS_CHECK_RETURN_CRITICAL
 static int ssl_get_handshake_transcript_sha256( mbedtls_ssl_context *ssl,
                                                 unsigned char *dst,
                                                 size_t dst_len,
@@ -5044,6 +5065,7 @@
     return( PSA_SUCCESS );
 }
 
+MBEDTLS_CHECK_RETURN_CRITICAL
 static int tls_prf_generic( mbedtls_md_type_t md_type,
                             const unsigned char *secret, size_t slen,
                             const char *label,
@@ -5120,6 +5142,7 @@
 
 #else /* MBEDTLS_USE_PSA_CRYPTO */
 
+MBEDTLS_CHECK_RETURN_CRITICAL
 static int tls_prf_generic( mbedtls_md_type_t md_type,
                             const unsigned char *secret, size_t slen,
                             const char *label,
@@ -5212,6 +5235,7 @@
 #endif /* MBEDTLS_USE_PSA_CRYPTO */
 
 #if defined(MBEDTLS_SHA256_C)
+MBEDTLS_CHECK_RETURN_CRITICAL
 static int tls_prf_sha256( const unsigned char *secret, size_t slen,
                            const char *label,
                            const unsigned char *random, size_t rlen,
@@ -5223,6 +5247,7 @@
 #endif /* MBEDTLS_SHA256_C */
 
 #if defined(MBEDTLS_SHA384_C)
+MBEDTLS_CHECK_RETURN_CRITICAL
 static int tls_prf_sha384( const unsigned char *secret, size_t slen,
                            const char *label,
                            const unsigned char *random, size_t rlen,
@@ -5242,6 +5267,7 @@
  * Outputs:
  * - the tls_prf, calc_verify and calc_finished members of handshake structure
  */
+MBEDTLS_CHECK_RETURN_CRITICAL
 static int ssl_set_handshake_prfs( mbedtls_ssl_handshake_params *handshake,
                                    mbedtls_md_type_t hash )
 {
@@ -5286,6 +5312,7 @@
  *      EMS: passed to calc_verify (debug + session_negotiate)
  *      PSA-PSA: conf
  */
+MBEDTLS_CHECK_RETURN_CRITICAL
 static int ssl_compute_master( mbedtls_ssl_handshake_params *handshake,
                                unsigned char *master,
                                const mbedtls_ssl_context *ssl )
@@ -5754,6 +5781,7 @@
 #endif /* !MBEDTLS_USE_PSA_CRYPTO && MBEDTLS_KEY_EXCHANGE_SOME_PSK_ENABLED */
 
 #if defined(MBEDTLS_SSL_SRV_C) && defined(MBEDTLS_SSL_RENEGOTIATION)
+MBEDTLS_CHECK_RETURN_CRITICAL
 static int ssl_write_hello_request( mbedtls_ssl_context *ssl );
 
 #if defined(MBEDTLS_SSL_PROTO_DTLS)
@@ -5925,6 +5953,7 @@
 #if defined(MBEDTLS_SSL_RENEGOTIATION) && defined(MBEDTLS_SSL_CLI_C)
 
 #if defined(MBEDTLS_SSL_KEEP_PEER_CERTIFICATE)
+MBEDTLS_CHECK_RETURN_CRITICAL
 static int ssl_check_peer_crt_unchanged( mbedtls_ssl_context *ssl,
                                          unsigned char *crt_buf,
                                          size_t crt_buf_len )
@@ -5940,6 +5969,7 @@
     return( memcmp( peer_crt->raw.p, crt_buf, peer_crt->raw.len ) );
 }
 #else /* MBEDTLS_SSL_KEEP_PEER_CERTIFICATE */
+MBEDTLS_CHECK_RETURN_CRITICAL
 static int ssl_check_peer_crt_unchanged( mbedtls_ssl_context *ssl,
                                          unsigned char *crt_buf,
                                          size_t crt_buf_len )
@@ -5974,6 +6004,7 @@
  * Once the certificate message is read, parse it into a cert chain and
  * perform basic checks, but leave actual verification to the caller
  */
+MBEDTLS_CHECK_RETURN_CRITICAL
 static int ssl_parse_certificate_chain( mbedtls_ssl_context *ssl,
                                         mbedtls_x509_crt *chain )
 {
@@ -6129,6 +6160,7 @@
 }
 
 #if defined(MBEDTLS_SSL_SRV_C)
+MBEDTLS_CHECK_RETURN_CRITICAL
 static int ssl_srv_check_client_no_crt_notification( mbedtls_ssl_context *ssl )
 {
     if( ssl->conf->endpoint == MBEDTLS_SSL_IS_CLIENT )
@@ -6154,6 +6186,7 @@
  */
 #define SSL_CERTIFICATE_EXPECTED 0
 #define SSL_CERTIFICATE_SKIP     1
+MBEDTLS_CHECK_RETURN_CRITICAL
 static int ssl_parse_certificate_coordinate( mbedtls_ssl_context *ssl,
                                              int authmode )
 {
@@ -6183,6 +6216,7 @@
     return( SSL_CERTIFICATE_EXPECTED );
 }
 
+MBEDTLS_CHECK_RETURN_CRITICAL
 static int ssl_parse_certificate_verify( mbedtls_ssl_context *ssl,
                                          int authmode,
                                          mbedtls_x509_crt *chain,
@@ -6373,6 +6407,7 @@
 }
 
 #if !defined(MBEDTLS_SSL_KEEP_PEER_CERTIFICATE)
+MBEDTLS_CHECK_RETURN_CRITICAL
 static int ssl_remember_peer_crt_digest( mbedtls_ssl_context *ssl,
                                          unsigned char *start, size_t len )
 {
@@ -6404,6 +6439,7 @@
     return( ret );
 }
 
+MBEDTLS_CHECK_RETURN_CRITICAL
 static int ssl_remember_peer_pubkey( mbedtls_ssl_context *ssl,
                                      unsigned char *start, size_t len )
 {
@@ -7072,6 +7108,7 @@
  *      [in] optionally used for:
  *        - MBEDTLS_DEBUG_C: ssl->conf->{f,p}_dbg
  */
+MBEDTLS_CHECK_RETURN_CRITICAL
 static int ssl_tls12_populate_transform( mbedtls_ssl_transform *transform,
                                    int ciphersuite,
                                    const unsigned char master[48],
@@ -7873,6 +7910,7 @@
     return( used );
 }
 
+MBEDTLS_CHECK_RETURN_CRITICAL
 static int ssl_session_load_tls12( mbedtls_ssl_session *session,
                                    const unsigned char *buf,
                                    size_t len )