diff --git a/lib/base/threadpool.cpp b/lib/base/threadpool.cpp
index c79e2143b..8423f2aca 100644
--- a/lib/base/threadpool.cpp
+++ b/lib/base/threadpool.cpp
@@ -192,6 +192,7 @@ void ThreadPool::QueueThreadProc(int tid)
 #endif /* _DEBUG */
 	}
 
+	boost::mutex::scoped_lock lock(m_Mutex);
 	UpdateThreadUtilization(tid, ThreadDead);
 	m_ThreadStats[tid].Zombie = false;
 }