diff --git a/libavformat/mov.c b/libavformat/mov.c
index cd56df5b29..e6c2dca0ba 100644
--- a/libavformat/mov.c
+++ b/libavformat/mov.c
@@ -4700,6 +4700,8 @@ static int mov_read_chap(MOVContext *c, AVIOContext *pb, MOVAtom atom)
     for (i = 0; i < num && !pb->eof_reached; i++)
         c->chapter_tracks[i] = avio_rb32(pb);
 
+    c->nb_chapter_tracks = i;
+
     return 0;
 }