diff --git a/libavformat/mov.c b/libavformat/mov.c
index 4b684cec3f..413a508b64 100644
--- a/libavformat/mov.c
+++ b/libavformat/mov.c
@@ -1913,6 +1913,7 @@ static int mov_read_stts(MOVContext *c, AVIOContext *pb, MOVAtom atom)
     if (entries >= UINT_MAX / sizeof(*sc->stts_data))
         return -1;
 
+    av_free(sc->stts_data);
     sc->stts_data = av_malloc(entries * sizeof(*sc->stts_data));
     if (!sc->stts_data)
         return AVERROR(ENOMEM);