diff --git a/CHANGELOG.md b/CHANGELOG.md
index c192635f..80de414c 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -55,6 +55,9 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 
 ## Fixed
 
+- TCP TMTC Server: `MutexGuard` was not created properly in
+  `TcpTmTcServer::handleTmSending(socket_t connSocket, bool& tmSent)` call.
+  PR: https://egit.irs.uni-stuttgart.de/fsfw/fsfw/pulls/618
 - Fix infinite recursion in `prepareHealthSetReply` of PUS Health Service 201.
   Is not currently used right now but might be used in the future
   PR: https://egit.irs.uni-stuttgart.de/fsfw/fsfw/pulls/617
diff --git a/src/fsfw/osal/common/TcpTmTcServer.cpp b/src/fsfw/osal/common/TcpTmTcServer.cpp
index 2e6910c5..91cb9574 100644
--- a/src/fsfw/osal/common/TcpTmTcServer.cpp
+++ b/src/fsfw/osal/common/TcpTmTcServer.cpp
@@ -19,6 +19,8 @@
 #include <ws2tcpip.h>
 #elif defined(PLATFORM_UNIX)
 #include <netdb.h>
+
+#include <utility>
 #endif
 
 const std::string TcpTmTcServer::DEFAULT_SERVER_PORT = tcpip::DEFAULT_SERVER_PORT;
@@ -29,7 +31,7 @@ TcpTmTcServer::TcpTmTcServer(object_id_t objectId, object_id_t tmtcTcpBridge,
     : SystemObject(objectId),
       tmtcBridgeId(tmtcTcpBridge),
       receptionMode(receptionMode),
-      tcpConfig(customTcpServerPort),
+      tcpConfig(std::move(customTcpServerPort)),
       receptionBuffer(receptionBufferSize),
       ringBuffer(ringBufferSize, true) {}
 
@@ -103,7 +105,7 @@ ReturnValue_t TcpTmTcServer::initialize() {
 
 TcpTmTcServer::~TcpTmTcServer() { closeSocket(listenerTcpSocket); }
 
-ReturnValue_t TcpTmTcServer::performOperation(uint8_t opCode) {
+[[noreturn]] ReturnValue_t TcpTmTcServer::performOperation(uint8_t opCode) {
   using namespace tcpip;
   // If a connection is accepted, the corresponding socket will be assigned to the new socket
   socket_t connSocket = 0;
@@ -138,7 +140,6 @@ ReturnValue_t TcpTmTcServer::performOperation(uint8_t opCode) {
     closeSocket(connSocket);
     connSocket = 0;
   }
-  return HasReturnvaluesIF::RETURN_OK;
 }
 
 ReturnValue_t TcpTmTcServer::initializeAfterTaskCreation() {
@@ -159,7 +160,7 @@ void TcpTmTcServer::handleServerOperation(socket_t& connSocket) {
 #endif
 
   while (true) {
-    int retval = recv(connSocket, reinterpret_cast<char*>(receptionBuffer.data()),
+    ssize_t retval = recv(connSocket, reinterpret_cast<char*>(receptionBuffer.data()),
                       receptionBuffer.capacity(), tcpConfig.tcpFlags);
     if (retval == 0) {
       size_t availableReadData = ringBuffer.getAvailableReadData();
@@ -252,17 +253,17 @@ ReturnValue_t TcpTmTcServer::handleTcReception(uint8_t* spacePacket, size_t pack
   return result;
 }
 
-std::string TcpTmTcServer::getTcpPort() const { return tcpConfig.tcpPort; }
+const std::string& TcpTmTcServer::getTcpPort() const { return tcpConfig.tcpPort; }
 
-void TcpTmTcServer::setSpacePacketParsingOptions(std::vector<uint16_t> validPacketIds) {
-  this->validPacketIds = validPacketIds;
+void TcpTmTcServer::setSpacePacketParsingOptions(std::vector<uint16_t> validPacketIds_) {
+  this->validPacketIds = std::move(validPacketIds_);
 }
 
 TcpTmTcServer::TcpConfig& TcpTmTcServer::getTcpConfigStruct() { return tcpConfig; }
 
 ReturnValue_t TcpTmTcServer::handleTmSending(socket_t connSocket, bool& tmSent) {
   // Access to the FIFO is mutex protected because it is filled by the bridge
-  MutexGuard(tmtcBridge->mutex, tmtcBridge->timeoutType, tmtcBridge->mutexTimeoutMs);
+  MutexGuard mg(tmtcBridge->mutex, tmtcBridge->timeoutType, tmtcBridge->mutexTimeoutMs);
   store_address_t storeId;
   while ((not tmtcBridge->tmFifo->empty()) and
          (tmtcBridge->packetSentCounter < tmtcBridge->sentPacketsPerCycle)) {
@@ -283,7 +284,7 @@ ReturnValue_t TcpTmTcServer::handleTmSending(socket_t connSocket, bool& tmSent)
 #endif
       arrayprinter::print(storeAccessor.data(), storeAccessor.size());
     }
-    int retval = send(connSocket, reinterpret_cast<const char*>(storeAccessor.data()),
+    ssize_t retval = send(connSocket, reinterpret_cast<const char*>(storeAccessor.data()),
                       storeAccessor.size(), tcpConfig.tcpTmFlags);
     if (retval == static_cast<int>(storeAccessor.size())) {
       // Packet sent, clear FIFO entry
@@ -339,6 +340,9 @@ ReturnValue_t TcpTmTcServer::handleTcRingBufferData(size_t availableReadData) {
   size_t foundSize = 0;
   size_t readLen = 0;
   while (readLen < readAmount) {
+    if(spacePacketParser == nullptr) {
+      return HasReturnvaluesIF::RETURN_FAILED;
+    }
     result =
         spacePacketParser->parseSpacePackets(bufPtrPtr, readAmount, startIdx, foundSize, readLen);
     switch (result) {
diff --git a/src/fsfw/osal/common/TcpTmTcServer.h b/src/fsfw/osal/common/TcpTmTcServer.h
index d062a0ce..faf6e0a1 100644
--- a/src/fsfw/osal/common/TcpTmTcServer.h
+++ b/src/fsfw/osal/common/TcpTmTcServer.h
@@ -17,6 +17,7 @@
 #endif
 
 #include <string>
+#include <utility>
 #include <vector>
 
 class TcpTmTcBridge;
@@ -44,7 +45,7 @@ class TcpTmTcServer : public SystemObject, public TcpIpBase, public ExecutableOb
 
   struct TcpConfig {
    public:
-    TcpConfig(std::string tcpPort) : tcpPort(tcpPort) {}
+    explicit TcpConfig(std::string tcpPort) : tcpPort(std::move(tcpPort)) {}
 
     /**
      * Passed to the recv call
@@ -84,7 +85,7 @@ class TcpTmTcServer : public SystemObject, public TcpIpBase, public ExecutableOb
                 size_t ringBufferSize = RING_BUFFER_SIZE,
                 std::string customTcpServerPort = DEFAULT_SERVER_PORT,
                 ReceptionModes receptionMode = ReceptionModes::SPACE_PACKETS);
-  virtual ~TcpTmTcServer();
+  ~TcpTmTcServer() override;
 
   void enableWiretapping(bool enable);
 
@@ -97,10 +98,10 @@ class TcpTmTcServer : public SystemObject, public TcpIpBase, public ExecutableOb
   void setSpacePacketParsingOptions(std::vector<uint16_t> validPacketIds);
 
   ReturnValue_t initialize() override;
-  ReturnValue_t performOperation(uint8_t opCode) override;
+  [[noreturn]] ReturnValue_t performOperation(uint8_t opCode) override;
   ReturnValue_t initializeAfterTaskCreation() override;
 
-  std::string getTcpPort() const;
+  [[nodiscard]] const std::string& getTcpPort() const;
 
  protected:
   StorageManagerIF* tcStore = nullptr;
@@ -115,7 +116,7 @@ class TcpTmTcServer : public SystemObject, public TcpIpBase, public ExecutableOb
 
   ReceptionModes receptionMode;
   TcpConfig tcpConfig;
-  struct sockaddr tcpAddress;
+  struct sockaddr tcpAddress = {};
   socket_t listenerTcpSocket = 0;
 
   MessageQueueId_t targetTcDestination = MessageQueueIF::NO_QUEUE;