diff --git a/library/ssl_tls.c b/library/ssl_tls.c
index d2dfa00..34d6bd5 100644
--- a/library/ssl_tls.c
+++ b/library/ssl_tls.c
@@ -2055,6 +2055,16 @@
 
     if( ssl->in_msglen == 0 )
     {
+#if defined(MBEDTLS_SSL_PROTO_TLS1_2)
+        if( ssl->minor_ver == MBEDTLS_SSL_MINOR_VERSION_3
+            && ssl->in_msgtype != MBEDTLS_SSL_MSG_APPLICATION_DATA )
+        {
+            /* TLS v1.2 explicitly disallows zero-length messages which are not application data */
+            MBEDTLS_SSL_DEBUG_MSG( 1, ( "invalid zero-length message type: %d", ssl->in_msgtype ) );
+            return( MBEDTLS_ERR_SSL_INVALID_RECORD );
+        }
+#endif /* MBEDTLS_SSL_PROTO_TLS1_2 */
+
         ssl->nb_zero++;
 
         /*