diff --git a/skeletons/constr_SET_OF.c b/skeletons/constr_SET_OF.c
index 3bebf7d..b3428bf 100644
--- a/skeletons/constr_SET_OF.c
+++ b/skeletons/constr_SET_OF.c
@@ -461,7 +461,7 @@
 	|| cb(" ::= {\n", 7, app_key))
 		return -1;
 
-	(void *)list = sptr;
+	(const void *)list = sptr;
 	for(i = 0; i < list->count; i++) {
 		const void *memb_ptr = list->array[i];
 		if(!memb_ptr) continue;
@@ -524,7 +524,7 @@
 		return -1;
 	}
 
-	(void *)list = sptr;
+	(const void *)list = sptr;
 
 	for(i = 0; i < list->count; i++) {
 		const void *memb_ptr = list->array[i];