diff --git a/libavformat/matroskaenc.c b/libavformat/matroskaenc.c
index 82624b740d..11174f1a3d 100644
--- a/libavformat/matroskaenc.c
+++ b/libavformat/matroskaenc.c
@@ -620,7 +620,7 @@ static int mkv_write_tracks(AVFormatContext *s)
             continue;
         }
 
-        if (!bit_depth)
+        if (!bit_depth && codec->codec_id != AV_CODEC_ID_ADPCM_G726)
             bit_depth = av_get_bytes_per_sample(codec->sample_fmt) << 3;
         if (!bit_depth)
             bit_depth = codec->bits_per_coded_sample;