diff --git a/lib/transports/polling-xhr.js b/lib/transports/polling-xhr.js
index <HASH>..<HASH> 100644
--- a/lib/transports/polling-xhr.js
+++ b/lib/transports/polling-xhr.js
@@ -177,6 +177,7 @@ Request.prototype.create = function () {
     };
     this.xhr.onprogress = empty;
   } else {
+    this.xhr.withCredentials = true;
     this.xhr.onreadystatechange = function () {
       try {
         if (xhr.readyState != 4) return;
Fixed; make sure to send cookies in cross domain requests.