diff --git a/src/common/network/FrameQueue.cpp b/src/common/network/FrameQueue.cpp
index c1daca3c..3c855629 100644
--- a/src/common/network/FrameQueue.cpp
+++ b/src/common/network/FrameQueue.cpp
@@ -4,7 +4,7 @@
  * GPLv2 Open Source. Use is subject to license terms.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
- *  Copyright (C) 2023,2024 Bryan Biedenkapp, N2PLL
+ *  Copyright (C) 2023,2024,2025 Bryan Biedenkapp, N2PLL
  *
  */
 #include "Defines.h"
@@ -23,6 +23,12 @@ using namespace network::frame;
 #include <cassert>
 #include <cstring>
 
+// ---------------------------------------------------------------------------
+//  Static Class Members
+// ---------------------------------------------------------------------------
+
+std::mutex FrameQueue::m_fqTimestampLock;
+
 // ---------------------------------------------------------------------------
 //  Public Class Members
 // ---------------------------------------------------------------------------
@@ -170,6 +176,7 @@ void FrameQueue::enqueueMessage(const uint8_t* message, uint32_t length, uint32_
 
 void FrameQueue::clearTimestamps()
 {
+    std::lock_guard<std::mutex> lock(m_fqTimestampLock);
     m_streamTimestamps.clear();
 }
 
@@ -187,6 +194,7 @@ uint8_t* FrameQueue::generateMessage(const uint8_t* message, uint32_t length, ui
 
     uint32_t timestamp = INVALID_TS;
     if (streamId != 0U) {
+        std::lock_guard<std::mutex> lock(m_fqTimestampLock);
         auto entry = m_streamTimestamps.find(streamId);
         if (entry != m_streamTimestamps.end()) {
             timestamp = entry->second;
@@ -221,6 +229,7 @@ uint8_t* FrameQueue::generateMessage(const uint8_t* message, uint32_t length, ui
     }
 
     if (streamId != 0U && rtpSeq == RTP_END_OF_CALL_SEQ) {
+        std::lock_guard<std::mutex> lock(m_fqTimestampLock);
         auto entry = m_streamTimestamps.find(streamId);
         if (entry != m_streamTimestamps.end()) {
             if (m_debug)
diff --git a/src/common/network/FrameQueue.h b/src/common/network/FrameQueue.h
index 3a23ff43..413c69d9 100644
--- a/src/common/network/FrameQueue.h
+++ b/src/common/network/FrameQueue.h
@@ -4,7 +4,7 @@
  * GPLv2 Open Source. Use is subject to license terms.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
- *  Copyright (C) 2023,2024 Bryan Biedenkapp, N2PLL
+ *  Copyright (C) 2023,2024,2025 Bryan Biedenkapp, N2PLL
  *
  */
 /**
@@ -21,6 +21,7 @@
 #include "common/network/RTPFNEHeader.h"
 #include "common/network/RawFrameQueue.h"
 
+#include <mutex>
 #include <unordered_map>
 
 namespace network
@@ -116,6 +117,7 @@ namespace network
     private:
         uint32_t m_peerId;
         std::unordered_map<uint32_t, uint32_t> m_streamTimestamps;
+        static std::mutex m_fqTimestampLock;
 
         /**
          * @brief Generate RTP message for the frame queue.