diff --git a/libavformat/mov.c b/libavformat/mov.c
index fdb29a01bf4a212759fe030d4adc82debae1a8aa..96a99280e17d70c91776ae3a6d6df08e0445bfe2 100644
--- a/libavformat/mov.c
+++ b/libavformat/mov.c
@@ -1471,6 +1471,11 @@ static int mov_read_stts(MOVContext *c, AVIOContext *pb, MOVAtom atom)
 
         sample_count=avio_rb32(pb);
         sample_duration = avio_rb32(pb);
+        /* sample_duration < 0 is invalid based on the spec */
+        if (sample_duration < 0) {
+            av_log(c->fc, AV_LOG_ERROR, "Invalid SampleDelta in STTS %d", sample_duration);
+            sample_duration = 1;
+        }
         sc->stts_data[i].count= sample_count;
         sc->stts_data[i].duration= sample_duration;