diff --git a/include/Client.h b/include/Client.h
index 27dae43..cbf3748 100644
--- a/include/Client.h
+++ b/include/Client.h
@@ -58,6 +58,7 @@ public:
     [[nodiscard]] std::queue<std::string>& MissedPacketQueue() { return mMissedPacketsDuringSyncing; }
     [[nodiscard]] const std::queue<std::string>& MissedPacketQueue() const { return mMissedPacketsDuringSyncing; }
     [[nodiscard]] size_t MissedPacketQueueSize() const { return mMissedPacketsDuringSyncing.size(); }
+    [[nodiscard]] std::mutex& MissedPacketQueueMutex() const { return mMissedPacketsMutex; }
     void SetIsConnected(bool NewIsConnected) { mIsConnected = NewIsConnected; }
     [[nodiscard]] TServer& Server() const;
     void UpdatePingTime();
@@ -68,7 +69,7 @@ private:
     bool mIsConnected = false;
     bool mIsSynced = false;
     bool mIsSyncing = false;
-    std::mutex mMissedPacketsMutex;
+    mutable std::mutex mMissedPacketsMutex;
     std::queue<std::string> mMissedPacketsDuringSyncing;
     std::set<std::string> mIdentifiers;
     bool mIsGuest = false;
diff --git a/src/TNetwork.cpp b/src/TNetwork.cpp
index c7719c8..28bf5cc 100644
--- a/src/TNetwork.cpp
+++ b/src/TNetwork.cpp
@@ -338,6 +338,7 @@ std::shared_ptr<TClient> TNetwork::CreateClient(SOCKET TCPSock) {
 
 bool TNetwork::TCPSend(TClient& c, const std::string& Data, bool IsSync) {
     if (!IsSync) {
+        std::unique_lock Lock(c.MissedPacketQueueMutex());
         if (c.IsSyncing()) {
             c.EnqueueMissedPacketDuringSyncing(Data);
             return true;