diff --git a/src/objects.cc b/src/objects.cc
index 87853f3805..a30d6ab0d1 100644
--- a/src/objects.cc
+++ b/src/objects.cc
@@ -1976,12 +1976,11 @@ void JSObject::EnqueueChangeRecord(Handle<JSObject> object,
                                    const char* type_str,
                                    Handle<Name> name,
                                    Handle<Object> old_value) {
+  ASSERT(!object->IsJSGlobalProxy());
+  ASSERT(!object->IsJSGlobalObject());
   Isolate* isolate = object->GetIsolate();
   HandleScope scope(isolate);
   Handle<String> type = isolate->factory()->InternalizeUtf8String(type_str);
-  if (object->IsJSGlobalObject()) {
-    object = handle(JSGlobalObject::cast(*object)->global_receiver(), isolate);
-  }
   Handle<Object> args[] = { type, object, name, old_value };
   int argc = name.is_null() ? 2 : old_value->IsTheHole() ? 3 : 4;
 
@@ -5927,6 +5926,8 @@ MaybeHandle<Object> JSObject::Freeze(Handle<JSObject> object) {
 
 
 void JSObject::SetObserved(Handle<JSObject> object) {
+  ASSERT(!object->IsJSGlobalProxy());
+  ASSERT(!object->IsJSGlobalObject());
   Isolate* isolate = object->GetIsolate();
   Handle<Map> new_map;
   Handle<Map> old_map(object->map(), isolate);
diff --git a/src/runtime.cc b/src/runtime.cc
index e07876b84b..e5df51e2e1 100644
--- a/src/runtime.cc
+++ b/src/runtime.cc
@@ -14883,12 +14883,7 @@ RUNTIME_FUNCTION(Runtime_IsObserved) {
 
   if (!args[0]->IsJSReceiver()) return isolate->heap()->false_value();
   CONVERT_ARG_CHECKED(JSReceiver, obj, 0);
-  if (obj->IsJSGlobalProxy()) {
-    Object* proto = obj->GetPrototype();
-    if (proto->IsNull()) return isolate->heap()->false_value();
-    ASSERT(proto->IsJSGlobalObject());
-    obj = JSReceiver::cast(proto);
-  }
+  ASSERT(!obj->IsJSGlobalProxy() || !obj->map()->is_observed());
   return isolate->heap()->ToBoolean(obj->map()->is_observed());
 }
 
@@ -14897,12 +14892,7 @@ RUNTIME_FUNCTION(Runtime_SetIsObserved) {
   HandleScope scope(isolate);
   ASSERT(args.length() == 1);
   CONVERT_ARG_HANDLE_CHECKED(JSReceiver, obj, 0);
-  if (obj->IsJSGlobalProxy()) {
-    Object* proto = obj->GetPrototype();
-    if (proto->IsNull()) return isolate->heap()->undefined_value();
-    ASSERT(proto->IsJSGlobalObject());
-    obj = handle(JSReceiver::cast(proto));
-  }
+  ASSERT(!obj->IsJSGlobalProxy());
   if (obj->IsJSProxy())
     return isolate->heap()->undefined_value();