diff --git a/lib/renderer/window-setup.ts b/lib/renderer/window-setup.ts
index 05d434d77a1..500168e3cfc 100644
--- a/lib/renderer/window-setup.ts
+++ b/lib/renderer/window-setup.ts
@@ -28,19 +28,19 @@ const toString = (value: any) => {
   return value != null ? `${value}` : value
 }
 
-const windowProxies: Record<number, BrowserWindowProxy> = {}
+const windowProxies = new Map<number, BrowserWindowProxy>()
 
 const getOrCreateProxy = (guestId: number) => {
-  let proxy = windowProxies[guestId]
+  let proxy = windowProxies.get(guestId)
   if (proxy == null) {
     proxy = new BrowserWindowProxy(guestId)
-    windowProxies[guestId] = proxy
+    windowProxies.set(guestId, proxy)
   }
   return proxy
 }
 
 const removeProxy = (guestId: number) => {
-  delete windowProxies[guestId]
+  windowProxies.delete(guestId)
 }
 
 type LocationProperties = 'hash' | 'href' | 'host' | 'hostname' | 'origin' | 'pathname' | 'port' | 'protocol' | 'search'