diff --git a/player.h b/player.h
index 00793a92..28b0341b 100644
--- a/player.h
+++ b/player.h
@@ -133,7 +133,7 @@ typedef struct {
   int32_t last_seqno_read;
   // mutexes and condition variables
   pthread_cond_t flowcontrol;
-  pthread_mutex_t ab_mutex, flush_mutex;
+  pthread_mutex_t ab_mutex, flush_mutex, volume_control_mutex;
   int fix_volume;
   uint32_t timestamp_epoch, last_timestamp,
       maximum_timestamp_interval; // timestamp_epoch of zero means not initialised, could start at 2