diff --git a/su4sml/src/wfcpog/liskov_constraint.sml b/su4sml/src/wfcpog/liskov_constraint.sml
index 1aa1a30..dcb5802 100644
--- a/su4sml/src/wfcpog/liskov_constraint.sml
+++ b/su4sml/src/wfcpog/liskov_constraint.sml
@@ -198,7 +198,7 @@ fun conjugate_invariants_help [] model = []
     let
 	(* get the invariants of all parents *)
         val parents = parents_of class model
- 	val invs = List.map (fn a => Predicate(Variable(varcounter.nextStr(),Rep_Core.type_of a),Rep_Core.type_of a,name_of_inv a,[selfarg (Rep_Core.type_of a)])) parents 
+ 	val invs = List.map (fn a => Predicate(Variable(varcounter.nextStr(),Rep_Core.type_of a),Rep_Core.type_of a,name_of_inv a,[])) parents 
     in
 	if (List.length(invs) = 0)
 	then (conjugate_invariants_help clist model)