diff --git a/toolkit/components/passwordmgr/test/test_bug_627616.html b/toolkit/components/passwordmgr/test/test_bug_627616.html
index eaa2d8982d98..7b498bfdfac5 100644
--- a/toolkit/components/passwordmgr/test/test_bug_627616.html
+++ b/toolkit/components/passwordmgr/test/test_bug_627616.html
@@ -31,11 +31,13 @@
         login2 = Cc["@mozilla.org/login-manager/loginInfo;1"].createInstance(Ci.nsILoginInfo);
         login2.init("http://mochi.test:8888", null, "mochirealm", "user1name", "user1pass", "", "");
         pwmgr.addLogin(login2);
+        startCallbackTimer();
     }
     function cleanup() {
         var pwmgr = Cc["@mozilla.org/login-manager;1"].getService(Ci.nsILoginManager);
         pwmgr.removeLogin(login);        
         pwmgr.removeLogin(login2);
+        timer.cancel();
     }
 
     function makeXHR(expectedStatus, expectedText, extra) {
@@ -59,7 +61,6 @@
     function testNonAnonymousCredentials() {
       var xhr = makeXHR(200, "OK");
       xhr.send();
-      startCallbackTimer();
     }
 
     function testAnonymousCredentials() {
@@ -77,10 +78,14 @@
       xhr.send();
     }
 
+    var gExpectedDialogs = 0;
     var gCurrentTest;
     function runNextTest() {
+      is(gExpectedDialogs, 0, "received expected number of auth dialogs");
+      Cc["@mozilla.org/network/http-auth-manager;1"].getService(Components.interfaces.nsIHttpAuthManager).clearAll();
       if (pendingTests.length > 0) {
-        gCurrentTest = pendingTests.shift();
+        ({expectedDialogs: gExpectedDialogs,
+          test: gCurrentTest}) = pendingTests.shift();
         gCurrentTest.call(this);
       } else {
         cleanup();
@@ -88,8 +93,9 @@
       }
     }
 
-    var pendingTests = [testNonAnonymousCredentials, testAnonymousCredentials,
-                        testAnonymousNoAuth];
+    var pendingTests = [{expectedDialogs: 2, test: testNonAnonymousCredentials},
+                        {expectedDialogs: 1, test: testAnonymousCredentials},
+                        {expectedDialogs: 0, test: testAnonymousNoAuth}];
     init();
     runNextTest();
 
@@ -97,9 +103,8 @@
     {
         var dialog = doc.getElementById("commonDialog");
         dialog.acceptDialog();
-        if (gCurrentTest == testNonAnonymousCredentials) {
-          startCallbackTimer();
-        }
+        gExpectedDialogs--;
+        startCallbackTimer();
     }
 </script>
 </body>