--- a/docshell/test/browser/browser_bug670318.js
+++ b/docshell/test/browser/browser_bug670318.js
@@ -26,16 +26,17 @@ add_task(function* test() {
             addEventListener("load", function onLoad() {
               removeEventListener("load", onLoad, true);
 
               Assert.ok(history.index < history.count, "history.index is valid");
               testDone.resolve();
             }, true);
 
             history.removeSHistoryListener(listener);
+            delete content._testListener;
             content.setTimeout(() => { content.location.reload(); }, 0);
           }
 
           return true;
         },
 
         OnHistoryReload: () => true,
         OnHistoryGoBack: () => true,
@@ -50,13 +51,20 @@ add_task(function* test() {
           return true;
         },
 
         QueryInterface: XPCOMUtils.generateQI([Ci.nsISHistoryListener,
                                                Ci.nsISupportsWeakReference])
       };
 
       history.addSHistoryListener(listener);
+      // Since listener implements nsISupportsWeakReference, we are
+      // responsible for keeping it alive so that the GC doesn't clear
+      // it before the test completes. We do this by anchoring the listener
+      // to the content global window, and clearing it just before the test
+      // completes.
+      content._testListener = listener;
       content.location = URL;
+
       yield testDone.promise;
     });
   });
 });