--- a/suite/common/utilityOverlay.js
+++ b/suite/common/utilityOverlay.js
@@ -570,17 +570,17 @@ function goClickThrobber(urlPref, aEvent
 {
   var url = GetLocalizedStringPref(urlPref);
   if (url)
     openUILinkIn(url, whereToOpenLink(aEvent, false, true, true));
 }
 
 function getTopWin()
 {
-  return gPrivate || Services.wm.getMostRecentWindow("navigator:browser");
+  return top.gPrivate || Services.wm.getMostRecentWindow("navigator:browser");
 }
 
 function isRestricted( url )
 {
   try {
     const nsIURIFixup = Components.interfaces.nsIURIFixup;
     var uri = Components.classes["@mozilla.org/docshell/urifixup;1"]
                         .getService(nsIURIFixup)