diff --git a/dom/tests/mochitest/ajax/prototype/test/lib/unittest.js b/dom/tests/mochitest/ajax/prototype/test/lib/unittest.js
index 8fba3057d69..b961ca98ec1 100644
--- a/dom/tests/mochitest/ajax/prototype/test/lib/unittest.js
+++ b/dom/tests/mochitest/ajax/prototype/test/lib/unittest.js
@@ -215,11 +215,13 @@ Test.Unit.Runner = Class.create({
     var test = this.tests[this.currentTest], actions;
     
     if (!test) return this.finish();
+    if (test.timerID > 0) test.timerID = -1;
     if (!test.isWaiting) this.logger.start(test.name);
     test.run();
     if (test.isWaiting) {
       this.logger.message("Waiting for " + test.timeToWait + "ms");
-      setTimeout(this.runTests.bind(this), test.timeToWait || 1000);
+      test.runner = this;
+      test.timerID = setTimeout(this.runTests.bind(this), test.timeToWait || 1000);
       return;
     }
     
@@ -487,6 +489,8 @@ Test.Unit.Testcase = Class.create(Test.Unit.Assertions, {
   
   isWaiting:  false,
   timeToWait: 1000,
+  timerID:   -1,
+  runner:     null,
   assertions: 0,
   failures:   0,
   errors:     0,
@@ -498,6 +502,17 @@ Test.Unit.Testcase = Class.create(Test.Unit.Assertions, {
     this.timeToWait = time;
   },
   
+  cancelWait: function() {
+    if (this.timerID > 0) {
+      clearTimeout(this.timerID);
+      this.timerID = -1;
+      this.test = function(){};
+      // continue test
+      if (this.runner)
+        this.runner.runTests();
+    }
+  },
+
   run: function(rethrow) {
     try {
       try {
diff --git a/dom/tests/mochitest/ajax/prototype/test/unit/ajax_test.js b/dom/tests/mochitest/ajax/prototype/test/unit/ajax_test.js
index 6a26b71fa32..9d004650f24 100644
--- a/dom/tests/mochitest/ajax/prototype/test/unit/ajax_test.js
+++ b/dom/tests/mochitest/ajax/prototype/test/unit/ajax_test.js
@@ -49,23 +49,30 @@ new Test.Unit.Runner({
   testUpdater: function() {
     this.assertEqual("", $("content").innerHTML);
     
-    new Ajax.Updater("content", "../fixtures/content.html", { method:'get' });
-    
+    new Ajax.Updater("content", "../fixtures/content.html", { method:'get', onComplete: function() {
+        this.assertEqual(sentence, $("content").innerHTML.strip().toLowerCase());
+        $('content').update('');
+        this.assertEqual("", $("content").innerHTML);
+        new Ajax.Updater({ success:"content", failure:"content2" },
+          "../fixtures/content.html",
+          { method:'get', parameters:{ pet:'monkey' }, onComplete: function() {
+            this.assertEqual(sentence, $("content").innerHTML.strip().toLowerCase());
+            this.assertEqual("", $("content2").innerHTML);
+            $('content').update('');
+            this.assertEqual("", $("content").innerHTML);
+            new Ajax.Updater("", "../fixtures/content.html",
+              { method:'get', parameters:"pet=monkey", onComplete: function() {
+                this.assertEqual("", $("content").innerHTML);
+                this.cancelWait();
+              }.bind(this)
+            });
+          }.bind(this)
+        });
+      }.bind(this)
+    });
+
     this.wait(1000, function() {
-      this.assertEqual(sentence, $("content").innerHTML.strip().toLowerCase());
-      
-      $('content').update('');
-      this.assertEqual("", $("content").innerHTML);
-       
-      new Ajax.Updater({ success:"content", failure:"content2" },
-        "../fixtures/content.html", { method:'get', parameters:{ pet:'monkey' } });
-      
-      new Ajax.Updater("", "../fixtures/content.html", { method:'get', parameters:"pet=monkey" });
-      
-      this.wait(1000, function() {
-	// bug 452706        this.assertEqual(sentence, $("content").innerHTML.strip().toLowerCase());
-        this.assertEqual("", $("content2").innerHTML);
-      });
+      this.flunk("The request was timeouted.");
     }); 
   },