diff --git a/libavformat/matroskadec.c b/libavformat/matroskadec.c
index b6a98931ef..e6776367ef 100644
--- a/libavformat/matroskadec.c
+++ b/libavformat/matroskadec.c
@@ -2087,7 +2087,6 @@ matroska_read_header (AVFormatContext    *s,
                 } else {
                     extradata_size = 2;
                 }
-                track->default_duration = 1024*1000 / audiotrack->internal_samplerate;
             }
 
             else if (codec_id == CODEC_ID_TTA) {