diff --git a/libavformat/mov.c b/libavformat/mov.c
index 3eafbf1d87..f7628820b0 100644
--- a/libavformat/mov.c
+++ b/libavformat/mov.c
@@ -2863,6 +2863,10 @@ static int mov_read_stsz(MOVContext *c, AVIOContext *pb, MOVAtom atom)
 
     for (i = 0; i < entries && !pb->eof_reached; i++) {
         sc->sample_sizes[i] = get_bits_long(&gb, field_size);
+        if (sc->sample_sizes[i] < 0) {
+            av_log(c->fc, AV_LOG_ERROR, "Invalid sample size %d\n", sc->sample_sizes[i]);
+            return AVERROR_INVALIDDATA;
+        }
         sc->data_size += sc->sample_sizes[i];
     }