diff --git a/baselines/dom.generated.d.ts b/baselines/dom.generated.d.ts
index 7a980ebbd..e3cda759c 100644
--- a/baselines/dom.generated.d.ts
+++ b/baselines/dom.generated.d.ts
@@ -17050,6 +17050,7 @@ interface Window extends EventTarget, WindowTimers, WindowSessionStorage, Window
     addEventListener(type: string, listener: EventListenerOrEventListenerObject, options?: boolean | AddEventListenerOptions): void;
     removeEventListener<K extends keyof WindowEventMap>(type: K, listener: (this: Window, ev: WindowEventMap[K]) => any, options?: boolean | EventListenerOptions): void;
     removeEventListener(type: string, listener: EventListenerOrEventListenerObject, options?: boolean | EventListenerOptions): void;
+    [index: number]: Window;
 }
 
 declare var Window: {
diff --git a/inputfiles/addedTypes.json b/inputfiles/addedTypes.json
index 10a1da38f..e1c1ec003 100644
--- a/inputfiles/addedTypes.json
+++ b/inputfiles/addedTypes.json
@@ -517,6 +517,9 @@
                 },
                 "implements": [
                     "WindowEventHandlers"
+                ],
+                "override-index-signatures": [
+                    "[index: number]: Window"
                 ]
             },
             "URLSearchParams": {