diff --git a/library/ssl_tls.c b/library/ssl_tls.c
index 7dd55bf..b388156 100644
--- a/library/ssl_tls.c
+++ b/library/ssl_tls.c
@@ -3495,6 +3495,8 @@
         MBEDTLS_SSL_DEBUG_MSG( 1, ( "unknown record type" ) );
 
 #if defined(MBEDTLS_SSL_PROTO_DTLS)
+        /* Silently ignore invalid DTLS records as recommended by RFC 6347
+         * Section 4.1.2.7 */
         if( ssl->conf->transport != MBEDTLS_SSL_TRANSPORT_DATAGRAM )
 #endif /* MBEDTLS_SSL_PROTO_DTLS */
             mbedtls_ssl_send_alert_message( ssl, MBEDTLS_SSL_ALERT_LEVEL_FATAL,