diff --git a/libavformat/matroskaenc.c b/libavformat/matroskaenc.c
index 4fd30b86fb..38518e3443 100644
--- a/libavformat/matroskaenc.c
+++ b/libavformat/matroskaenc.c
@@ -640,7 +640,6 @@ static int mkv_write_tracks(AVFormatContext *s)
                     int d_width = codec->width*av_q2d(st->sample_aspect_ratio);
                     put_ebml_uint(pb, MATROSKA_ID_VIDEODISPLAYWIDTH , d_width);
                     put_ebml_uint(pb, MATROSKA_ID_VIDEODISPLAYHEIGHT, codec->height);
-                    put_ebml_uint(pb, MATROSKA_ID_VIDEODISPLAYUNIT, 3);
                 }
 
                 if (codec->codec_id == AV_CODEC_ID_RAWVIDEO) {