diff --git a/libavformat/movenc.c b/libavformat/movenc.c
index 158dfa8b67..a19c64b652 100644
--- a/libavformat/movenc.c
+++ b/libavformat/movenc.c
@@ -2751,6 +2751,8 @@ static int mov_write_sidx_tag(AVIOContext *pb,
         }
     } else {
         entries = track->nb_frag_info;
+        if (entries <= 0)
+            return 0;
         presentation_time = track->frag_info[0].time;
     }