diff --git a/player/AudioSRC.cpp b/player/AudioSRC.cpp
index cb091c46..2af4433f 100644
--- a/player/AudioSRC.cpp
+++ b/player/AudioSRC.cpp
@@ -113,6 +113,7 @@ int AudioPlayer::getPCMChannel() {
 }
 
 int AudioPlayer::getPCMData(char *buf, int size) {
+    lock_guard<mutex> lck(_mtx);
     if (_buffer.size() < size) {
         return 0;
     }
@@ -121,6 +122,7 @@ int AudioPlayer::getPCMData(char *buf, int size) {
     return size;
 }
 
-void AudioPlayer::inputFrame(const char *data, size_t size){
+void AudioPlayer::inputFrame(const char *data, size_t size) {
+    lock_guard<mutex> lck(_mtx);
     _buffer.append(data, size);
 }
diff --git a/player/AudioSRC.h b/player/AudioSRC.h
index 54324847..1b552d09 100644
--- a/player/AudioSRC.h
+++ b/player/AudioSRC.h
@@ -79,6 +79,7 @@ private:
 private:
     int _sample_rate, _channel;
     SDL_AudioFormat _format;
+    mutex _mtx;
     BufferLikeString _buffer;
     SDLAudioDevice::Ptr _device;
 };