diff --git a/libavcodec/hdrenc.c b/libavcodec/hdrenc.c
index 20e42134bc..a7bf36946d 100644
--- a/libavcodec/hdrenc.c
+++ b/libavcodec/hdrenc.c
@@ -124,7 +124,7 @@ static int hdr_encode_frame(AVCodecContext *avctx, AVPacket *pkt,
     uint8_t *buf;
     int ret;
 
-    packet_size = avctx->width * avctx->height * 4LL + 1024LL;
+    packet_size = avctx->height * 4LL + avctx->width * avctx->height * 8LL + 1024LL;
     if ((ret = ff_get_encode_buffer(avctx, pkt, packet_size, 0)) < 0)
         return ret;