diff --git a/index.html b/index.html
index d126bd7..fc876e4 100644
--- a/index.html
+++ b/index.html
@@ -2165,7 +2165,7 @@ <h2>
         [Exposed=Window]
 
         interface GamepadEvent: Event {
-          constructor(DOMString type, GamepadEventInit eventInitDict);
+          constructor(DOMString type, optional GamepadEventInit eventInitDict = {});
           [SameObject] readonly attribute Gamepad gamepad;
         };
       </pre>
@@ -2184,7 +2184,7 @@ <h3>
         </h3>
         <pre class="idl" data-cite="DOM">
         dictionary GamepadEventInit : EventInit {
-          required Gamepad gamepad;
+          Gamepad? gamepad = null;
         };
       </pre>
         <dl data-dfn-for="GamepadEventInit">