diff --git a/baselines/dom.generated.d.ts b/baselines/dom.generated.d.ts
index 73f009bdf..11e5fafbb 100644
--- a/baselines/dom.generated.d.ts
+++ b/baselines/dom.generated.d.ts
@@ -12854,7 +12854,7 @@ interface Window extends EventTarget, WindowTimers, WindowSessionStorage, Window
     readonly devicePixelRatio: number;
     readonly doNotTrack: string;
     readonly document: Document;
-    event: Event;
+    event: Event | undefined;
     readonly external: External;
     readonly frameElement: Element;
     readonly frames: Window;
@@ -14303,7 +14303,7 @@ declare var defaultStatus: string;
 declare var devicePixelRatio: number;
 declare var doNotTrack: string;
 declare var document: Document;
-declare var event: Event;
+declare var event: Event | undefined;
 declare var external: External;
 declare var frameElement: Element;
 declare var frames: Window;
diff --git a/inputfiles/overridingTypes.json b/inputfiles/overridingTypes.json
index ffab8ea3f..00eef78fc 100644
--- a/inputfiles/overridingTypes.json
+++ b/inputfiles/overridingTypes.json
@@ -1,4 +1,10 @@
  [
+    {
+        "kind": "property",
+        "interface": "Window",
+        "name": "event",
+        "type": "Event | undefined"
+    },
     {
         "kind": "method",
         "interface": "Node",