diff --git a/cpp/src/server/Server.h b/cpp/src/server/Server.h
index 2c912c3e91e4bfa22df1d6f3172267504e9b0edb..30ea95a7bb007aade869e674d00ca9751501e8b6 100644
--- a/cpp/src/server/Server.h
+++ b/cpp/src/server/Server.h
@@ -21,7 +21,6 @@
 
 #include <cstdint>
 #include <string>
-#include <mutex>
 
 
 namespace zilliz {
diff --git a/cpp/src/utils/SignalUtil.cpp b/cpp/src/utils/SignalUtil.cpp
index 8677016cf365ddb44f9245341633400994e63fab..6c68f702d20312628308b341e10dd0e7d2adb507 100644
--- a/cpp/src/utils/SignalUtil.cpp
+++ b/cpp/src/utils/SignalUtil.cpp
@@ -34,8 +34,8 @@ void SignalUtil::HandleSignal(int signum) {
         case SIGUSR2: {
             SERVER_LOG_INFO << "Server received signal: " << signum;
 
-            server::Server &server_ptr = server::Server::Instance();
-            server_ptr.Stop();
+            server::Server &server = server::Server::Instance();
+            server.Stop();
 
             exit(0);
         }
@@ -43,8 +43,8 @@ void SignalUtil::HandleSignal(int signum) {
             SERVER_LOG_INFO << "Server received critical signal: " << signum;
             SignalUtil::PrintStacktrace();
 
-            server::Server &server_ptr = server::Server::Instance();
-            server_ptr.Stop();
+            server::Server &server = server::Server::Instance();
+            server.Stop();
 
             exit(1);
         }