--- a/dom/media/MediaTimer.h
+++ b/dom/media/MediaTimer.h
@@ -8,16 +8,17 @@
 #define MediaTimer_h_
 
 #include "mozilla/AbstractThread.h"
 #include "mozilla/IntegerPrintfMacros.h"
 #include "mozilla/Monitor.h"
 #include "mozilla/MozPromise.h"
 #include "mozilla/RefPtr.h"
 #include "mozilla/TimeStamp.h"
+#include "mozilla/Unused.h"
 #include "nsITimer.h"
 #include <queue>
 
 namespace mozilla {
 
 extern LazyLogModule gMediaTimerLog;
 
 #define TIMER_LOG(x, ...) \