--- a/dom/media/gtest/TestMediaMIMETypes.cpp
+++ b/dom/media/gtest/TestMediaMIMETypes.cpp
@@ -1,15 +1,16 @@
 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 #include "gtest/gtest.h"
 #include "MediaMIMETypes.h"
+#include "mozilla/Unused.h"
 
 using namespace mozilla;
 
 TEST(MediaMIMETypes, DependentMIMEType)
 {
   static const struct
   {
     const char* mString;