--- a/dom/src/threads/test/test_threadErrors.html
+++ b/dom/src/threads/test/test_threadErrors.html
@@ -34,16 +34,17 @@ Tests of DOM Worker Threads (Bug 437152)
       SimpleTest.finish();
       return;
     }
 
     failedWorkers.push(event.target);
     actualErrorCount++;
 
     if (actualErrorCount == expectedErrorCount) {
+      ok(true, "all errors correctly detected");
       SimpleTest.finish();
     }
   };
 
   for (var i = 1; i <= expectedErrorCount; i++) {
     var worker = new Worker("threadErrors_worker" + i + ".js");
     worker.onmessage = messageListener;
     worker.onerror = errorListener;
@@ -51,9 +52,8 @@ Tests of DOM Worker Threads (Bug 437152)
   }
 
   SimpleTest.waitForExplicitFinish();
 
 </script>
 </pre>
 </body>
 </html>
-