diff --git a/libav/avienc.c b/libav/avienc.c
index cef541d7ba9a533bb6cf340793ee9c961541aec1..a580e5309849109846e16e656083603d0e24eb4f 100644
--- a/libav/avienc.c
+++ b/libav/avienc.c
@@ -340,7 +340,7 @@ static int avi_write_trailer(AVFormatContext *s)
         /* update file size */
         file_size = url_ftell(pb);
         url_fseek(pb, 4, SEEK_SET);
-        put_le32(pb, file_size);
+        put_le32(pb, file_size - 8);
         url_fseek(pb, file_size, SEEK_SET);
     }
     put_flush_packet(pb);