diff --git a/libavformat/utils.c b/libavformat/utils.c
index 45a4179552..807d9f10cb 100644
--- a/libavformat/utils.c
+++ b/libavformat/utils.c
@@ -2782,7 +2782,7 @@ static void estimate_timings_from_bit_rate(AVFormatContext *ic)
                 st      = ic->streams[i];
                 if (   st->time_base.num <= INT64_MAX / ic->bit_rate
                     && st->duration == AV_NOPTS_VALUE) {
-                    duration = av_rescale(8 * filesize, st->time_base.den,
+                    duration = av_rescale(filesize, 8LL * st->time_base.den,
                                           ic->bit_rate *
                                           (int64_t) st->time_base.num);
                     st->duration = duration;