diff --git a/testing/web-platform/mozilla/tests/fetch/fetchpriority/support/fetch-tests/fetch-init.h2.html b/testing/web-platform/mozilla/tests/fetch/fetchpriority/support/fetch-tests/fetch-init.h2.html
index d91dd5450f12..a4efa02e96a4 100644
--- a/testing/web-platform/mozilla/tests/fetch/fetchpriority/support/fetch-tests/fetch-init.h2.html
+++ b/testing/web-platform/mozilla/tests/fetch/fetchpriority/support/fetch-tests/fetch-init.h2.html
@@ -71,10 +71,11 @@
         request_init: {}
       },
     ];
+    let fetchResponses = [];
     for (const data of kData) {
-        const response = fetch(data.request_info, data.request_init);
-        opener.postMessage("ChildLoaded", "*");
+        fetchResponses.push(fetch(data.request_info, data.request_init));
     }
+    Promise.all(fetchResponses).finally(() => opener.postMessage("ChildLoaded", "*"));
   }
 </script>
 </body>