diff --git a/skeletons/REAL.c b/skeletons/REAL.c
index 4b73f4b..6a5e7cd 100644
--- a/skeletons/REAL.c
+++ b/skeletons/REAL.c
@@ -325,7 +325,7 @@
 asn_dec_rval_t
 REAL_decode_xer(asn_codec_ctx_t *opt_codec_ctx,
 	asn_TYPE_descriptor_t *td, void **sptr, const char *opt_mname,
-		void *buf_ptr, size_t size) {
+		const void *buf_ptr, size_t size) {
 
 	return xer_decode_primitive(opt_codec_ctx, td,
 		sptr, sizeof(REAL_t), opt_mname,