diff --git a/libavformat/mov.c b/libavformat/mov.c
index 25562bb995..a95f9ea135 100644
--- a/libavformat/mov.c
+++ b/libavformat/mov.c
@@ -3041,10 +3041,10 @@ static int mov_read_stts(MOVContext *c, AVIOContext *pb, MOVAtom atom)
             sc->stts_data[i].duration = 1;
             corrected_dts += (delta_magnitude < 0 ? (int64_t)delta_magnitude : 1) * sample_count;
         } else {
-            corrected_dts += sample_duration * (int64_t)sample_count;
+            corrected_dts += sample_duration * (uint64_t)sample_count;
         }
 
-        current_dts += sc->stts_data[i].duration * (int64_t)sample_count;
+        current_dts += sc->stts_data[i].duration * (uint64_t)sample_count;
 
         if (current_dts > corrected_dts) {
             int64_t drift = (current_dts - corrected_dts)/FFMAX(sample_count, 1);