structure comparison functions
diff --git a/skeletons/constr_SET_OF.c b/skeletons/constr_SET_OF.c
index 51291b8..62973ac 100644
--- a/skeletons/constr_SET_OF.c
+++ b/skeletons/constr_SET_OF.c
@@ -953,3 +953,12 @@
 	return rv;
 }
 
+int
+SET_OF_compare(const asn_TYPE_descriptor_t *td, const void *aptr,
+               const void *bptr) {
+    (void)td;
+    (void)aptr;
+    (void)bptr;
+    /* Not implemented yet. */
+    return 0;
+}