diff --git a/src/lib/clpz.pl b/src/lib/clpz.pl
index 2c412ac3..daed1471 100644
--- a/src/lib/clpz.pl
+++ b/src/lib/clpz.pl
@@ -4369,9 +4369,11 @@ tuple_domain([T|Ts], Relation0) -->
         tuple_domain(Ts, Relation1).
 
 tuple_freeze(Tuple, Relation) :-
-        put_attr(R, clpz_relation, Relation),
-        make_propagator(rel_tuple(R, Tuple), Prop),
-        tuple_freeze_(Tuple, Prop).
+        (   ground(Tuple) -> true
+        ;   put_attr(R, clpz_relation, Relation),
+            make_propagator(rel_tuple(R, Tuple), Prop),
+            tuple_freeze_(Tuple, Prop)
+        ).
 
 tuple_freeze_([], _).
 tuple_freeze_([T|Ts], Prop) :-