diff --git a/libavformat/movenc.c b/libavformat/movenc.c
index 246fc2912c..402611e81e 100644
--- a/libavformat/movenc.c
+++ b/libavformat/movenc.c
@@ -6504,7 +6504,7 @@ static int mov_flush_fragment(AVFormatContext *s, int force)
                       av_rescale(mov->tracks[first_track].cluster[0].dts, AV_TIME_BASE, mov->tracks[first_track].timescale),
                       (has_video ? starts_with_key : mov->tracks[first_track].cluster[0].flags & MOV_SYNC_SAMPLE) ? AVIO_DATA_MARKER_SYNC_POINT : AVIO_DATA_MARKER_BOUNDARY_POINT);
 
-    for (i = 0; i < mov->nb_tracks; i++) {
+    for (i = first_track; i < mov->nb_tracks; i++) {
         MOVTrack *track = &mov->tracks[i];
         int buf_size, write_moof = 1, moof_tracks = -1;
         uint8_t *buf;