diff --git a/libavformat/matroskaenc.c b/libavformat/matroskaenc.c
index 2a8a2eaaa1..adca74f111 100644
--- a/libavformat/matroskaenc.c
+++ b/libavformat/matroskaenc.c
@@ -637,7 +637,7 @@ static int mkv_write_tracks(AVFormatContext *s)
                 }
 
                 if (st->sample_aspect_ratio.num) {
-                    int d_width = codec->width*av_q2d(st->sample_aspect_ratio);
+                    int d_width = av_rescale(codec->width, st->sample_aspect_ratio.num, st->sample_aspect_ratio.den);
                     put_ebml_uint(pb, MATROSKA_ID_VIDEODISPLAYWIDTH , d_width);
                     put_ebml_uint(pb, MATROSKA_ID_VIDEODISPLAYHEIGHT, codec->height);
                 }