diff --git a/skeletons/OCTET_STRING_oer.c b/skeletons/OCTET_STRING_oer.c
index 3a72166..c2f9a5c 100644
--- a/skeletons/OCTET_STRING_oer.c
+++ b/skeletons/OCTET_STRING_oer.c
@@ -11,7 +11,7 @@
 
 asn_dec_rval_t
 OCTET_STRING_decode_oer(const asn_codec_ctx_t *opt_codec_ctx,
-                        asn_TYPE_descriptor_t *td,
+                        const asn_TYPE_descriptor_t *td,
                         const asn_oer_constraints_t *constraints, void **sptr,
                         const void *ptr, size_t size) {
     const asn_OCTET_STRING_specifics_t *specs =
@@ -100,13 +100,14 @@
  * Encode as Canonical OER.
  */
 asn_enc_rval_t
-OCTET_STRING_encode_oer(asn_TYPE_descriptor_t *td,
-                        const asn_oer_constraints_t *constraints, void *sptr,
-                        asn_app_consume_bytes_f *cb, void *app_key) {
+OCTET_STRING_encode_oer(const asn_TYPE_descriptor_t *td,
+                        const asn_oer_constraints_t *constraints,
+                        const void *sptr, asn_app_consume_bytes_f *cb,
+                        void *app_key) {
     const asn_OCTET_STRING_specifics_t *specs =
         td->specifics ? (const asn_OCTET_STRING_specifics_t *)td->specifics
                       : &asn_SPC_OCTET_STRING_specs;
-    OCTET_STRING_t *st = (OCTET_STRING_t *)sptr;
+    const OCTET_STRING_t *st = (const OCTET_STRING_t *)sptr;
     const asn_oer_constraints_t *cts =
         constraints ? constraints : td->encoding_constraints.oer_constraints;
     ssize_t ct_size = cts ? cts->size : -1;