diff --git a/libavformat/mov.c b/libavformat/mov.c
index 004c4c47ea..93f369125a 100644
--- a/libavformat/mov.c
+++ b/libavformat/mov.c
@@ -401,6 +401,7 @@ static int mov_read_dref(MOVContext *c, AVIOContext *pb, MOVAtom atom)
     if (entries >= UINT_MAX / sizeof(*sc->drefs))
         return AVERROR_INVALIDDATA;
     av_free(sc->drefs);
+    sc->drefs_count = 0;
     sc->drefs = av_mallocz(entries * sizeof(*sc->drefs));
     if (!sc->drefs)
         return AVERROR(ENOMEM);