--- a/dom/presentation/Presentation.cpp
+++ b/dom/presentation/Presentation.cpp
@@ -1,14 +1,15 @@
 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
 /* vim:set ts=2 sw=2 sts=2 et cindent: */
 /* 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 <ctype.h>
 #include "mozilla/dom/PresentationBinding.h"
 #include "mozilla/dom/Promise.h"
 #include "nsContentUtils.h"
 #include "nsCycleCollectionParticipant.h"
 #include "nsIDocShell.h"
 #include "nsIPresentationService.h"
 #include "nsServiceManagerUtils.h"
 #include "Presentation.h"