diff --git a/webmessaging/broadcastchannel/sandbox.html b/webmessaging/broadcastchannel/sandbox.html
index 68e45b879481ee..aedf3c0d6fe64d 100644
--- a/webmessaging/broadcastchannel/sandbox.html
+++ b/webmessaging/broadcastchannel/sandbox.html
@@ -1,15 +1,16 @@
 <!DOCTYPE html>
 <meta charset=utf-8>
+<title>Creating BroadcastChannel in an opaque origin</title>
 <script src="/resources/testharness.js"></script>
 <script src="/resources/testharnessreport.js"></script>
 <body>
 <script>
 async_test(t => {
     self.onmessage = t.step_func(e => {
-        assert_true(e.data.startsWith('Exception: '));
+        assert_equals(e.data, 'Created');
         t.done();
       });
-  }, 'Creating BroadcastChannel in opaque origin should fail.');
+  });
 </script>
 <iframe sandbox="allow-scripts" src="resources/sandboxed.html"></iframe>
 </body>
