diff --git a/TCPServer.cpp b/TCPServer.cpp
index 46e98be..7f6f29e 100644
--- a/TCPServer.cpp
+++ b/TCPServer.cpp
@@ -108,7 +108,7 @@ namespace core {
       // below would deadlock on this non-recursive mutex.
       std::vector<TCPSession *> stale;
       {
-	 std::lock_guard<std::mutex> guard(lock);
+	 std::lock_guard guard(lock);
 	 for (auto &s : sessions)
 	    if (!s->hasReceivedData && (now - s->acceptedAt) > GRACE_PERIOD)
 	       stale.push_back(s.get());