diff --git a/dom/bindings/DOMJSProxyHandler.cpp b/dom/bindings/DOMJSProxyHandler.cpp
index f0ebf4385486..0b9444e0f2a3 100644
--- a/dom/bindings/DOMJSProxyHandler.cpp
+++ b/dom/bindings/DOMJSProxyHandler.cpp
@@ -112,8 +112,9 @@ DOMProxyHandler::EnsureExpandoObject(JSContext* cx, JS::Handle<JSObject*> obj)
     expandoAndGeneration = nullptr;
   }
 
+  JS::Rooted<JSObject*> parent(cx, js::GetObjectParent(obj));
   JS::Rooted<JSObject*> expando(cx,
-    JS_NewObjectWithGivenProto(cx, nullptr, JS::NullPtr()));
+    JS_NewObjectWithGivenProto(cx, nullptr, JS::NullPtr(), parent));
   if (!expando) {
     return nullptr;
   }