@@ -153,6 +153,7 @@ static AVIOContext * wtvfile_open_sector(int first_sector, uint64_t length, int

     AVIOContext *pb;

     WtvFile *wf;

     uint8_t *buffer;

+    int64_t size;

     if (seek_by_sector(s->pb, first_sector, 0) < 0)

         return NULL;

@@ -205,7 +206,8 @@ static AVIOContext * wtvfile_open_sector(int first_sector, uint64_t length, int

         return NULL;

     }

-    if ((int64_t)wf->sectors[wf->nb_sectors - 1] << WTV_SECTOR_BITS > avio_size(s->pb))

+    size = avio_size(s->pb);

+    if (size >= 0 && (int64_t)wf->sectors[wf->nb_sectors - 1] << WTV_SECTOR_BITS > size)

         av_log(s, AV_LOG_WARNING, "truncated file\n");

     /* check length */