diff --git a/libavcodec/wavpackenc.c b/libavcodec/wavpackenc.c
index 977bcf0e04..05e8f2bec9 100644
--- a/libavcodec/wavpackenc.c
+++ b/libavcodec/wavpackenc.c
@@ -2878,7 +2878,7 @@ static int wavpack_encode_frame(AVCodecContext *avctx, AVPacket *avpkt,
     }
 
     buf_size = s->block_samples * avctx->channels * 8
-             + 200 /* for headers */;
+             + 200 * avctx->channels /* for headers */;
     if ((ret = ff_alloc_packet2(avctx, avpkt, buf_size, 0)) < 0)
         return ret;
     buf = avpkt->data;