diff --git a/libavformat/g729dec.c b/libavformat/g729dec.c
index 51112f5618..9c92ea4fcf 100644
--- a/libavformat/g729dec.c
+++ b/libavformat/g729dec.c
@@ -43,7 +43,7 @@ static int g729_read_header(AVFormatContext *s)
     st->codecpar->codec_type  = AVMEDIA_TYPE_AUDIO;
     st->codecpar->codec_id    = AV_CODEC_ID_G729;
     st->codecpar->sample_rate = 8000;
-    st->codecpar->channels    = 1;
+    st->codecpar->ch_layout   = (AVChannelLayout)AV_CHANNEL_LAYOUT_MONO;
 
     if (s1 && s1->bit_rate)
         s->bit_rate = s1->bit_rate;