diff --git a/lib/transports/polling-xhr.js b/lib/transports/polling-xhr.js
index deaf1615..27188c14 100644
--- a/lib/transports/polling-xhr.js
+++ b/lib/transports/polling-xhr.js
@@ -248,6 +248,9 @@ Request.prototype.onError = function(err){
  */
 
 Request.prototype.cleanup = function(){
+  if ('undefined' == typeof this.xhr ) {
+    return;
+  }
   // xmlhttprequest
   this.xhr.onreadystatechange = empty;