diff --git a/lib/application.js b/lib/application.js
index 5667e0eb..a98bd331 100644
--- a/lib/application.js
+++ b/lib/application.js
@@ -565,7 +565,11 @@ app.listen = function(cb) {
       (arguments.length == 1 && typeof arguments[0] == 'function');
 
   if (useAppConfig) {
-    server.listen(this.get('port'), this.get('host'), cb);
+    var port = this.get('port');
+    // NOTE(bajtos) port:undefined no longer works on node@6,
+    // we must pass port:0 explicitly
+    if (port === undefined) port = 0;
+    server.listen(port, this.get('host'), cb);
   } else {
     server.listen.apply(server, arguments);
   }