diff --git a/src/prolog/examples/bimetatrans_ruleml.pl b/src/prolog/examples/bimetatrans_ruleml.pl
index 7c0028d5..ea56c2e2 100644
--- a/src/prolog/examples/bimetatrans_ruleml.pl
+++ b/src/prolog/examples/bimetatrans_ruleml.pl
@@ -283,10 +283,13 @@ sign('+') --> "+".
 
 double_quote('"') --> "\"".
 
-list_ws(String) -->
-    partial_string(String),
+list_ws(Ls) -->
+    list(Ls),
     ws.
 
+list([]) --> [].
+list([L|Ls]) --> [L], list(Ls).
+
 /*
  * ruleml_assert_item//1 specifies the elements of RuleML that may
  * appear as items in a RuleML Assert performative, an implicitly