diff --git a/library/ssl_tls13_keys.c b/library/ssl_tls13_keys.c
index 91cc4d9..8303cda 100644
--- a/library/ssl_tls13_keys.c
+++ b/library/ssl_tls13_keys.c
@@ -761,6 +761,7 @@
     return( 0 );
 }
 
+MBEDTLS_CHECK_RETURN_CRITICAL
 static int ssl_tls13_calc_finished_core( psa_algorithm_t hash_alg,
                                          unsigned char const *base_key,
                                          unsigned char const *transcript,
@@ -1188,6 +1189,7 @@
     return( 0 );
 }
 
+MBEDTLS_CHECK_RETURN_CRITICAL
 static int mbedtls_ssl_tls13_get_cipher_key_info(
                     const mbedtls_ssl_ciphersuite_t *ciphersuite_info,
                     size_t *key_len, size_t *iv_len )