diff --git a/WeaselIPCServer/WeaselServerImpl.cpp b/WeaselIPCServer/WeaselServerImpl.cpp
index 3b5075b42..11225c445 100644
--- a/WeaselIPCServer/WeaselServerImpl.cpp
+++ b/WeaselIPCServer/WeaselServerImpl.cpp
@@ -1,5 +1,6 @@
 #include "stdafx.h"
 #include "WeaselServerImpl.h"
+#include <mutex>
 #include <Windows.h>
 #include <resource.h>
 #include <WeaselUtility.h>
@@ -161,6 +162,8 @@ int ServerImpl::Stop() {
   return 0;
 }
 
+static std::mutex g_api_mutex;
+
 int ServerImpl::Run() {
   // This workaround causes a VC internal error:
   // void PipeServer::Listen(ServerHandler handler);
@@ -168,8 +171,8 @@ int ServerImpl::Run() {
   // auto handler = boost::bind(&ServerImpl::HandlePipeMessage, this);
   // auto listener = boost::bind(&PipeServer::Listen, channel.get(), handler);
   //
-
   auto listener = [this](PipeMessage msg, PipeServer::Respond resp) -> void {
+    std::lock_guard guard(g_api_mutex);
     HandlePipeMessage(msg, resp);
   };
   pipeThread = std::make_unique<boost::thread>(