--- a/netwerk/ipc/RemoteOpenFileChild.cpp
+++ b/netwerk/ipc/RemoteOpenFileChild.cpp
@@ -15,16 +15,20 @@
 #include "nsJARProtocolHandler.h"
 #include "nsIRemoteOpenFileListener.h"
 #include "nsProxyRelease.h"
 #include "SerializedLoadContext.h"
 
 // needed to alloc/free NSPR file descriptors
 #include "private/pprio.h"
 
+#if !defined(XP_WIN) && !defined(MOZ_WIDGET_COCOA)
+#include <unistd.h>
+#endif
+
 using namespace mozilla::ipc;
 
 namespace mozilla {
 namespace net {
 
 //-----------------------------------------------------------------------------
 // Helper class to dispatch events async on windows/OSX
 //-----------------------------------------------------------------------------