diff --git a/webrtc/base/messagequeue.h b/webrtc/base/messagequeue.h
index c3ab3b6..856a6eb 100644
--- a/webrtc/base/messagequeue.h
+++ b/webrtc/base/messagequeue.h
@@ -251,7 +251,7 @@
   MessageList msgq_;
   PriorityQueue dmsgq_;
   uint32_t dmsgq_next_num_;
-  mutable CriticalSection crit_;
+  CriticalSection crit_;
 
  private:
   RTC_DISALLOW_COPY_AND_ASSIGN(MessageQueue);