diff --git a/testing/web-platform/tests/interfaces/content-index.idl b/testing/web-platform/tests/interfaces/content-index.idl
index 4cd44f536d751..436f6d90e7557 100644
--- a/testing/web-platform/tests/interfaces/content-index.idl
+++ b/testing/web-platform/tests/interfaces/content-index.idl
@@ -39,7 +39,8 @@ dictionary ContentIndexEventInit : ExtendableEventInit {
   required DOMString id;
 };
 
-[Constructor(DOMString type, ContentIndexEventInit init), Exposed=ServiceWorker]
+[Exposed=ServiceWorker]
 interface ContentIndexEvent : ExtendableEvent {
+  constructor(DOMString type, ContentIndexEventInit init);
   readonly attribute DOMString id;
 };