diff --git a/tests/wpt/mozilla/tests/mozilla/mozbrowser/mozbrowserlocationchange_event.html b/tests/wpt/mozilla/tests/mozilla/mozbrowser/mozbrowserlocationchange_event.html
index c2ba1d3e4e8..3866cc6dadb 100644
--- a/tests/wpt/mozilla/tests/mozilla/mozbrowser/mozbrowserlocationchange_event.html
+++ b/tests/wpt/mozilla/tests/mozilla/mozbrowser/mozbrowserlocationchange_event.html
@@ -38,7 +38,7 @@ async_test(function(t) {
 
   var action_idx = 0;
 
-  iframe.addEventListener("mozbrowserlocationchange", e => {
+  iframe.addEventListener("mozbrowserlocationchange", t.step_func(e => {
     received_events.push(e.detail.url);
     received_events.push(e.detail.canGoBack);
     received_events.push(e.detail.canGoForward);
@@ -49,7 +49,7 @@ async_test(function(t) {
        assert_array_equals(received_events, expected_events);
        t.done();
     }
-  });
+  }));
 
   document.body.appendChild(iframe);