add const
diff --git a/skeletons/REAL.c b/skeletons/REAL.c
index f036dcd..0bdeb82 100644
--- a/skeletons/REAL.c
+++ b/skeletons/REAL.c
@@ -429,7 +429,7 @@
 }
 
 asn_dec_rval_t
-REAL_decode_xer(asn_codec_ctx_t *opt_codec_ctx,
+REAL_decode_xer(const asn_codec_ctx_t *opt_codec_ctx,
 	asn_TYPE_descriptor_t *td, void **sptr, const char *opt_mname,
 		const void *buf_ptr, size_t size) {
 
@@ -805,7 +805,7 @@
 #ifndef ASN_DISABLE_PER_SUPPORT
 
 asn_dec_rval_t
-REAL_decode_uper(asn_codec_ctx_t *opt_codec_ctx, asn_TYPE_descriptor_t *td,
+REAL_decode_uper(const asn_codec_ctx_t *opt_codec_ctx, asn_TYPE_descriptor_t *td,
                  const asn_per_constraints_t *constraints, void **sptr,
                  asn_per_data_t *pd) {
     (void)constraints;	/* No PER visible constraints */