diff --git a/libavcodec/h264.c b/libavcodec/h264.c
index fd9142918e..7f09154128 100644
--- a/libavcodec/h264.c
+++ b/libavcodec/h264.c
@@ -3791,7 +3791,7 @@ static int decode_nal_units(H264Context *h, const uint8_t *buf, int buf_size){
         int consumed;
         int dst_length;
         int bit_length;
-        uint8_t *ptr;
+        const uint8_t *ptr;
         int i, nalsize = 0;
         int err;