diff --git a/dom/base/nsDOMClassInfo.cpp b/dom/base/nsDOMClassInfo.cpp
index 7b1a656a660..e3e535697f2 100644
--- a/dom/base/nsDOMClassInfo.cpp
+++ b/dom/base/nsDOMClassInfo.cpp
@@ -1898,8 +1898,7 @@ ResolvePrototype(nsIXPConnect *aXPConnect, nsGlobalWindow *aWin, JSContext *cx,
       }
       dot_prototype = ::JS_NewObjectWithUniqueType(cx,
                                                    &sDOMConstructorProtoClass,
-                                                   proto,
-                                                   winobj);
+                                                   proto);
       NS_ENSURE_TRUE(dot_prototype, NS_ERROR_OUT_OF_MEMORY);
     }
   }
diff --git a/dom/bindings/BindingUtils.cpp b/dom/bindings/BindingUtils.cpp
index bb25932fd73..a77cd1d251e 100644
--- a/dom/bindings/BindingUtils.cpp
+++ b/dom/bindings/BindingUtils.cpp
@@ -614,7 +614,7 @@ CreateInterfacePrototypeObject(JSContext* cx, JS::Handle<JSObject*> global,
                                const NativeProperties* chromeOnlyProperties)
 {
   JS::Rooted<JSObject*> ourProto(cx,
-    JS_NewObjectWithUniqueType(cx, Jsvalify(protoClass), parentProto, global));
+    JS_NewObjectWithUniqueType(cx, Jsvalify(protoClass), parentProto));
   if (!ourProto ||
       !DefineProperties(cx, ourProto, properties, chromeOnlyProperties)) {
     return nullptr;
diff --git a/js/src/jsfriendapi.cpp b/js/src/jsfriendapi.cpp
index ce5b3dafa6c..8c1b536c2c2 100644
--- a/js/src/jsfriendapi.cpp
+++ b/js/src/jsfriendapi.cpp
@@ -127,8 +127,7 @@ JS_SplicePrototype(JSContext *cx, HandleObject obj, HandleObject proto)
 }
 
 JS_FRIEND_API(JSObject *)
-JS_NewObjectWithUniqueType(JSContext *cx, const JSClass *clasp, HandleObject proto,
-                           HandleObject parent)
+JS_NewObjectWithUniqueType(JSContext *cx, const JSClass *clasp, HandleObject proto)
 {
     /*
      * Create our object with a null proto and then splice in the correct proto
@@ -137,7 +136,7 @@ JS_NewObjectWithUniqueType(JSContext *cx, const JSClass *clasp, HandleObject pro
      * we're not going to be using that ObjectGroup anyway.
      */
     RootedObject obj(cx, NewObjectWithGivenProto(cx, (const js::Class *)clasp, NullPtr(),
-                                                 parent, SingletonObject));
+                                                 NullPtr(), SingletonObject));
     if (!obj)
         return nullptr;
     if (!JS_SplicePrototype(cx, obj, proto))
diff --git a/js/src/jsfriendapi.h b/js/src/jsfriendapi.h
index e6b064677dd..4687cf4a578 100644
--- a/js/src/jsfriendapi.h
+++ b/js/src/jsfriendapi.h
@@ -57,8 +57,7 @@ extern JS_FRIEND_API(bool)
 JS_SplicePrototype(JSContext *cx, JS::HandleObject obj, JS::HandleObject proto);
 
 extern JS_FRIEND_API(JSObject *)
-JS_NewObjectWithUniqueType(JSContext *cx, const JSClass *clasp, JS::HandleObject proto,
-                           JS::HandleObject parent);
+JS_NewObjectWithUniqueType(JSContext *cx, const JSClass *clasp, JS::HandleObject proto);
 
 // Allocate an object in exactly the same way as JS_NewObjectWithGivenProto, but
 // without invoking the metadata callback on it.  This allows creation of
diff --git a/js/xpconnect/src/XPCWrappedNativeProto.cpp b/js/xpconnect/src/XPCWrappedNativeProto.cpp
index 5831ee80f42..c2ffcb25d89 100644
--- a/js/xpconnect/src/XPCWrappedNativeProto.cpp
+++ b/js/xpconnect/src/XPCWrappedNativeProto.cpp
@@ -87,10 +87,10 @@ XPCWrappedNativeProto::Init(const XPCNativeScriptableCreateInfo* scriptableCreat
         jsclazz = &XPC_WN_NoMods_NoCall_Proto_JSClass;
     }
 
-    JS::RootedObject parent(cx, mScope->GetGlobalJSObject());
-    JS::RootedObject proto(cx, JS_GetObjectPrototype(cx, parent));
+    JS::RootedObject global(cx, mScope->GetGlobalJSObject());
+    JS::RootedObject proto(cx, JS_GetObjectPrototype(cx, global));
     mJSProtoObject = JS_NewObjectWithUniqueType(cx, js::Jsvalify(jsclazz),
-                                                proto, parent);
+                                                proto);
 
     bool success = !!mJSProtoObject;
     if (success) {