diff --git a/demux/demux.c b/demux/demux.c
index 650078d068..fdec805d15 100644
--- a/demux/demux.c
+++ b/demux/demux.c
@@ -4137,10 +4137,10 @@ static void update_cache(struct demux_internal *in)
         stream_control(stream, STREAM_CTRL_GET_METADATA, &stream_metadata);
     }
 
-    update_bytes_read(in);
-
     pthread_mutex_lock(&in->lock);
 
+    update_bytes_read(in);
+
     if (do_update)
         in->stream_size = stream_size;
     if (stream_metadata) {