diff --git a/services/audioflinger/IAfThread.h b/services/audioflinger/IAfThread.h
index 8596acb..abb8f2f 100644
--- a/services/audioflinger/IAfThread.h
+++ b/services/audioflinger/IAfThread.h
@@ -402,7 +402,7 @@
     // the Thread is not busy releasing the Tracks, during which the Thread mutex
     // may be temporarily unlocked.  Some Track methods will use this method to
     // avoid races.
-    virtual void waitWhileThreadBusy_l(audio_utils::unique_lock& ul)
+    virtual void waitWhileThreadBusy_l(audio_utils::unique_lock<audio_utils::mutex>& ul)
             REQUIRES(mutex()) = 0;
 
     // The ThreadloopExecutor is used to defer functors or dtors