--- a/browser/base/content/tabbrowser.xml
+++ b/browser/base/content/tabbrowser.xml
@@ -664,17 +664,17 @@
             onProgressChange(aWebProgress, aRequest,
                              aCurSelfProgress, aMaxSelfProgress,
                              aCurTotalProgress, aMaxTotalProgress) {
               this.mTotalProgress = aMaxTotalProgress ? aCurTotalProgress / aMaxTotalProgress : 0;
 
               if (!this._shouldShowProgress(aRequest))
                 return;
 
-              if (this.mTotalProgress && aWebProgress && aWebProgress.isTopLevel)
+              if (this.mTotalProgress && this.mTab.hasAttribute("busy"))
                 this.mTab.setAttribute("progress", "true");
 
               this._callProgressListeners("onProgressChange",
                                           [aWebProgress, aRequest,
                                            aCurSelfProgress, aMaxSelfProgress,
                                            aCurTotalProgress, aMaxTotalProgress]);
             },