diff --git a/index.bs b/index.bs
index a944fa9c..4d810f81 100644
--- a/index.bs
+++ b/index.bs
@@ -3707,7 +3707,7 @@ spec: storage; urlPrefix: https://storage.spec.whatwg.org/
 
       : Input
       :: |worker|, a [=/service worker=]
-      :: |event|, an [=event=]
+      :: |event|, an {{ExtendableEvent}}
       : Output
       :: None