diff --git a/libavcodec/shorten.c b/libavcodec/shorten.c
index 7aa656afcc..36e0d09188 100644
--- a/libavcodec/shorten.c
+++ b/libavcodec/shorten.c
@@ -268,7 +268,7 @@ static void decode_subframe_lpc(ShortenContext *s, int channel, int residual_siz
 
 static int shorten_decode_frame(AVCodecContext *avctx,
         void *data, int *data_size,
-        uint8_t *buf, int buf_size)
+        const uint8_t *buf, int buf_size)
 {
     ShortenContext *s = avctx->priv_data;
     int i, input_buf_size = 0;