diff --git a/browser/components/sessionstore/test/browser/browser_526613.js b/browser/components/sessionstore/test/browser/browser_526613.js
index ab3efbe97af..d4c0bd506a9 100644
--- a/browser/components/sessionstore/test/browser/browser_526613.js
+++ b/browser/components/sessionstore/test/browser/browser_526613.js
@@ -82,11 +82,16 @@ function test() {
       if (this.pass++ == 1) {  
         is(browserWindowsCount(), 2, "Two windows should exist at this point");
 
-        // executeSoon is needed here in order to let the first window be focused
-        // (see above)
-        executeSoon(function() {
+        // let the first window be focused (see above)
+        var fm = Cc["@mozilla.org/focus-manager;1"].getService(Ci.nsIFocusManager);
+        if (window == fm.activeWindow) {
           ss.setBrowserState(oldState);
-        });
+        } else {
+          window.addEventListener("activate", function () {
+            window.removeEventListener("activate", arguments.callee, false);
+            ss.setBrowserState(oldState);
+          }, false);
+        }
       }
       else {
         is(browserWindowsCount(), 1, "Only one window should exist after cleanup");