diff --git a/lib/transports/polling.js b/lib/transports/polling.js
index 2eaacd99..9863e455 100644
--- a/lib/transports/polling.js
+++ b/lib/transports/polling.js
@@ -205,7 +205,7 @@ Polling.prototype.uri = function(){
   var port = '';
 
   // cache busting is forced for IE / android / iOS6 ಠ_ಠ
-  if ('ActiveXObject' in window
+  if ('ActiveXObject' in global
     || util.ua.chromeframe
     || util.ua.android
     || util.ua.ios6