diff --git a/polimani.pl b/polimani.pl
index 06e7e9f..cdd7054 100644
--- a/polimani.pl
+++ b/polimani.pl
@@ -288,7 +288,7 @@ simplify_polynomial(P, P2) :-
     maplist(term_to_list, L9, L8),
     delete(L9, 0, L10),
     sort(0, @=<, L10, L11),
-    polynomial_to_list(P2, L11),
+    list_to_polynomial(L11, P2),
     !.
 %% Tests:
 %% ?- simplify_polynomial(1, X).