diff --git a/content/media/gmp/GMPPlatform.cpp b/content/media/gmp/GMPPlatform.cpp
index ad4a0acdd89c..bd841833f02a 100644
--- a/content/media/gmp/GMPPlatform.cpp
+++ b/content/media/gmp/GMPPlatform.cpp
@@ -276,13 +276,13 @@ GMPMutexImpl::Destroy()
 void
 GMPMutexImpl::Acquire()
 {
-  mMonitor.Lock();
+  mMonitor.Enter();
 }
 
 void
 GMPMutexImpl::Release()
 {
-  mMonitor.Unlock();
+  mMonitor.Exit();
 }
 
 } // namespace gmp
diff --git a/content/media/gmp/GMPPlatform.h b/content/media/gmp/GMPPlatform.h
index 5d595628608f..f3488b51b708 100644
--- a/content/media/gmp/GMPPlatform.h
+++ b/content/media/gmp/GMPPlatform.h
@@ -9,6 +9,7 @@
 #include "mozilla/Mutex.h"
 #include "gmp-platform.h"
 #include "base/thread.h"
+#include "mozilla/ReentrantMonitor.h"
 
 namespace mozilla {
 namespace gmp {
@@ -46,7 +47,7 @@ public:
   virtual void Destroy() MOZ_OVERRIDE;
 
 private:
-  Monitor mMonitor;
+  ReentrantMonitor mMonitor;
 };
 
 } // namespace gmp