diff --git a/library/ssl_tls.c b/library/ssl_tls.c
index 0099b43..7badec5 100644
--- a/library/ssl_tls.c
+++ b/library/ssl_tls.c
@@ -245,6 +245,7 @@
 }
 
 #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 );
@@ -337,6 +338,7 @@
  * Key material generation
  */
 #if defined(MBEDTLS_SSL_PROTO_SSL3)
+MBEDTLS_CHECK_RETURN_CRITICAL
 static int ssl3_prf( const unsigned char *secret, size_t slen,
                      const char *label,
                      const unsigned char *random, size_t rlen,
@@ -398,6 +400,7 @@
 #endif /* MBEDTLS_SSL_PROTO_SSL3 */
 
 #if defined(MBEDTLS_SSL_PROTO_TLS1) || defined(MBEDTLS_SSL_PROTO_TLS1_1)
+MBEDTLS_CHECK_RETURN_CRITICAL
 static int tls1_prf( const unsigned char *secret, size_t slen,
                      const char *label,
                      const unsigned char *random, size_t rlen,
@@ -605,6 +608,7 @@
     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,
@@ -679,6 +683,7 @@
 
 #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,
@@ -770,6 +775,7 @@
 }
 #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,
@@ -781,6 +787,7 @@
 #endif /* MBEDTLS_SHA256_C */
 
 #if defined(MBEDTLS_SHA512_C) && !defined(MBEDTLS_SHA512_NO_SHA384)
+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,
@@ -825,6 +832,7 @@
 
 #if defined(MBEDTLS_KEY_EXCHANGE_PSK_ENABLED) && \
     defined(MBEDTLS_USE_PSA_CRYPTO)
+MBEDTLS_CHECK_RETURN_CRITICAL
 static int ssl_use_opaque_psk( mbedtls_ssl_context const *ssl )
 {
     if( ssl->conf->f_psk != NULL )
@@ -949,6 +957,7 @@
  *        - MBEDTLS_SSL_EXPORT_KEYS: ssl->conf->{f,p}_export_keys
  *        - MBEDTLS_DEBUG_C: ssl->conf->{f,p}_dbg
  */
+MBEDTLS_CHECK_RETURN_CRITICAL
 static int ssl_populate_transform( mbedtls_ssl_transform *transform,
                                    int ciphersuite,
                                    const unsigned char master[48],
@@ -1512,6 +1521,7 @@
  * 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,
                                    int minor_ver,
                                    mbedtls_md_type_t hash )
@@ -1581,6 +1591,7 @@
  *      EMS: passed to calc_verify (debug + (SSL3) session_negotiate)
  *      PSA-PSA: minor_ver, conf
  */
+MBEDTLS_CHECK_RETURN_CRITICAL
 static int ssl_compute_master( mbedtls_ssl_handshake_params *handshake,
                                unsigned char *master,
                                const mbedtls_ssl_context *ssl )
@@ -2109,6 +2120,7 @@
 #endif /* 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)
@@ -2324,6 +2336,7 @@
 #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 )
@@ -2339,6 +2352,7 @@
     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 )
@@ -2373,6 +2387,7 @@
  * 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 )
 {
@@ -2522,6 +2537,7 @@
 }
 
 #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 )
@@ -2571,6 +2587,7 @@
  */
 #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 )
 {
@@ -2600,6 +2617,7 @@
     return( SSL_CERTIFICATE_EXPECTED );
 }
 
+MBEDTLS_CHECK_RETURN_CRITICAL
 static int ssl_parse_certificate_verify( mbedtls_ssl_context *ssl,
                                          int authmode,
                                          mbedtls_x509_crt *chain,
@@ -2790,6 +2808,7 @@
 }
 
 #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 )
 {
@@ -2821,6 +2840,7 @@
     return( ret );
 }
 
+MBEDTLS_CHECK_RETURN_CRITICAL
 static int ssl_remember_peer_pubkey( mbedtls_ssl_context *ssl,
                                      unsigned char *start, size_t len )
 {
@@ -3799,6 +3819,7 @@
     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 */
@@ -3876,6 +3897,7 @@
 
 #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 )
@@ -3889,6 +3911,7 @@
     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 )
@@ -4306,6 +4329,7 @@
 }
 
 /* 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 )
@@ -4474,6 +4498,7 @@
  * 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 )
@@ -5393,6 +5418,7 @@
  * verify_result is put before peer_cert so that all mandatory fields come
  * together in one block.
  */
+MBEDTLS_CHECK_RETURN_CRITICAL
 static int ssl_session_save( const mbedtls_ssl_session *session,
                              unsigned char omit_header,
                              unsigned char *buf,
@@ -5592,6 +5618,7 @@
  * 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,
@@ -5895,6 +5922,7 @@
 /*
  * 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;
@@ -6506,6 +6534,7 @@
  * 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 )