diff --git a/libavformat/mov_chan.c b/libavformat/mov_chan.c
index b1fa13f753..00a2a4bb92 100644
--- a/libavformat/mov_chan.c
+++ b/libavformat/mov_chan.c
@@ -579,9 +579,10 @@ int ff_mov_read_chan(AVFormatContext *s, AVIOContext *pb, AVStream *st,
             label_mask |= mask_incr;
         }
     }
-    if (layout_tag == 0)
-        st->codec->channel_layout = label_mask;
-    else
+    if (layout_tag == 0) {
+        if (label_mask)
+            st->codec->channel_layout = label_mask;
+    } else
         st->codec->channel_layout = ff_mov_get_channel_layout(layout_tag, bitmap);
 
     return 0;