diff --git a/conf/confbase.Y b/conf/confbase.Y
index 3e8f5807..3dd5fed7 100644
--- a/conf/confbase.Y
+++ b/conf/confbase.Y
@@ -94,7 +94,7 @@ CF_DECLS
   struct channel_limit cl;
   struct timeformat *tf;
   mpls_label_stack *mls;
-  struct bytestring *bs;
+  const struct bytestring *bs;
 }
 
 %token END CLI_MARKER INVALID_TOKEN ELSECOL DDOT
diff --git a/proto/radv/config.Y b/proto/radv/config.Y
index db683194..eeafe6f4 100644
--- a/proto/radv/config.Y
+++ b/proto/radv/config.Y
@@ -26,7 +26,7 @@ static list radv_dns_list;	/* Used by radv_rdnss and radv_dnssl */
 static u8 radv_mult_val;	/* Used by radv_mult for second return value */
 
 static inline void
-radv_add_to_custom_list(list *l, int type, struct bytestring *payload)
+radv_add_to_custom_list(list *l, int type, const struct bytestring *payload)
 {
   if (type < 0 || type > 255) cf_error("RA cusom type must be in range 0-255");
   struct radv_custom_config *cf = cfg_allocz(sizeof(struct radv_custom_config));
diff --git a/proto/radv/radv.h b/proto/radv/radv.h
index 8c716158..2baf0bad 100644
--- a/proto/radv/radv.h
+++ b/proto/radv/radv.h
@@ -129,7 +129,7 @@ struct radv_custom_config
 {
   node n;
   u8 type;			/* Identifier of the type of option */
-  struct bytestring *payload;	/* Payload of the option */
+  const struct bytestring *payload;	/* Payload of the option */
 };
 
 /*