diff --git a/content/media/EncodedBufferCache.h b/content/media/EncodedBufferCache.h
index a4276b8dcfd1..763d979b379d 100644
--- a/content/media/EncodedBufferCache.h
+++ b/content/media/EncodedBufferCache.h
@@ -45,7 +45,7 @@ private:
   // File handle for the temporary file
   PRFileDesc* mFD;
   // Used to protect the mEncodedBuffer for avoiding AppendBuffer/Consume on different thread at the same time.
-  Mutex mMutex;;
+  Mutex mMutex;
   // the current buffer size can be read
   uint64_t mDataSize;
   // The maximal buffer allowed in memory