--- a/dom/tests/mochitest/whatwg/test_bug500328.html
+++ b/dom/tests/mochitest/whatwg/test_bug500328.html
@@ -111,17 +111,17 @@ function onChildLoad(e) {
     statusMsg("Got load for " + getURLFromEvent(e) + ", but not calling gGen.next() because gCallbackOnIframeLoad was false.");
   }
 }
 
 function onChildPageShow(e) {
   if(gCallbackOnIframePageShow) {
     statusMsg("Got pageshow for " + getURLFromEvent(e) + ".  About to call gGen.next().");
     gCallbackOnIframePageShow = false;
-    gGen.next();
+    SimpleTest.executeSoon(function() { gGen.next(); });
   }
   else {
     statusMsg("Got pageshow for " + getURLFromEvent(e) + ", but not calling gGen.next() because gCallbackOnIframePageShow was false.");
   }
 }
 
 function enableChildLoadCallback() {
   gCallbackOnIframeLoad = true;