diff --git a/libavcodec/xsubenc.c b/libavcodec/xsubenc.c
index bb2cdb0529..53f4d6c3a9 100644
--- a/libavcodec/xsubenc.c
+++ b/libavcodec/xsubenc.c
@@ -206,6 +206,8 @@ static av_cold int xsub_encoder_init(AVCodecContext *avctx)
     if (!avctx->codec_tag)
         avctx->codec_tag = MKTAG('D','X','S','B');
 
+    avctx->bits_per_coded_sample = 4;
+
     return 0;
 }