diff --git a/tiramisu/setting.py b/tiramisu/setting.py
index ded7811..ecfc5bf 100644
--- a/tiramisu/setting.py
+++ b/tiramisu/setting.py
@@ -289,15 +289,15 @@ class Setting(object):
                 properties.remove('frozen')
 
         if properties != frozenset():
-            comment = (opt_or_descr._name, str(list(properties)))
+            props = list(properties)
             if 'frozen' in properties:
                 raise PropertiesOptionError(_('cannot change the value for '
                                               'option {0} this option is frozen'
-                                              '').format(comment))
+                                              '').format(opt_or_descr._name), props)
             else:
                 raise PropertiesOptionError(_("trying to access to an option "
                                               "named: {0} with properties {1}"
-                                              "").format(comment, list(properties)))
+                                              "").format(opt_or_descr._name, str(props)), props)
 
     def _get_permissive(self, opt=None):
         return self._permissives.get(opt, frozenset())