--- a/security/sandbox/linux/SandboxOpenedFiles.cpp
+++ b/security/sandbox/linux/SandboxOpenedFiles.cpp
@@ -4,16 +4,17 @@
  * 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 "SandboxOpenedFiles.h"
 
 #include "mozilla/Move.h"
 #include "SandboxLogging.h"
 
+#include <errno.h>
 #include <fcntl.h>
 #include <unistd.h>
 
 namespace mozilla {
 
 // The default move constructor almost works, but Atomic isn't
 // move-constructable and the fd needs some special handling.
 SandboxOpenedFile::SandboxOpenedFile(SandboxOpenedFile&& aMoved)