diff --git a/library/ssl_tls.c b/library/ssl_tls.c
index abad0b3..d9ab832 100644
--- a/library/ssl_tls.c
+++ b/library/ssl_tls.c
@@ -7653,8 +7653,7 @@
 #if defined(MBEDTLS_SSL_PROTO_TLS1) || defined(MBEDTLS_SSL_PROTO_TLS1_1)
 #if defined(MBEDTLS_MD5_C)
         case MBEDTLS_SSL_HASH_MD5:
-            ssl->handshake->calc_verify = ssl_calc_verify_tls;
-            break;
+            return MBEDTLS_ERR_SSL_INVALID_VERIFY_HASH;
 #endif
 #if defined(MBEDTLS_SHA1_C)
         case MBEDTLS_SSL_HASH_SHA1: