diff --git a/src/chargepoint/requestfifo/RequestFifoManager.cpp b/src/chargepoint/requestfifo/RequestFifoManager.cpp
index 7992413b..b8a3d730 100644
--- a/src/chargepoint/requestfifo/RequestFifoManager.cpp
+++ b/src/chargepoint/requestfifo/RequestFifoManager.cpp
@@ -99,6 +99,8 @@ void RequestFifoManager::requestQueued()
 /** @brief Process a FIFO request */
 void RequestFifoManager::processFifoRequest()
 {
+    std::lock_guard lock(m_process_mutex);
+  
     // Check the connection state
     if (m_msg_sender.isConnected())
     {
diff --git a/src/chargepoint/requestfifo/RequestFifoManager.h b/src/chargepoint/requestfifo/RequestFifoManager.h
index 23966b5f..bcbd4c4b 100644
--- a/src/chargepoint/requestfifo/RequestFifoManager.h
+++ b/src/chargepoint/requestfifo/RequestFifoManager.h
@@ -19,6 +19,8 @@ along with OpenOCPP. If not, see <http://www.gnu.org/licenses/>.
 #ifndef OPENOCPP_REQUESTFIFOMANAGER_H
 #define OPENOCPP_REQUESTFIFOMANAGER_H
 
+#include <mutex>
+
 #include "IRequestFifo.h"
 #include "Timer.h"
 
@@ -99,6 +101,9 @@ class RequestFifoManager : public ocpp::messages::IRequestFifo::IListener
     /** @brief Retry count for the current request */
     unsigned int m_request_retry_count;
 
+    /** @brief Mutex protectiing against concurrent processFifoRequest calls */
+    std::mutex m_process_mutex;
+
     /** @brief Process a FIFO request */
     void processFifoRequest();
 };