diff --git a/tiramisu/option/option.py b/tiramisu/option/option.py
index f97847f..c6d3ec4 100644
--- a/tiramisu/option/option.py
+++ b/tiramisu/option/option.py
@@ -266,14 +266,13 @@ class Option(BaseOption):
                       option_bag: OptionBag,
                       check_error: bool=True,
                       loaded: bool=False,
-                      ) -> None:
+                      ) -> bool:
         """Return True if value is really valid
         If not validate or invalid return it returns False
         """
         config_bag = option_bag.config_bag
         force_index = option_bag.index
         is_warnings_only = getattr(self, '_warnings_only', False)
-
         if check_error and config_bag is not undefined and \
                 not 'validator' in config_bag.properties:
             return False
@@ -363,9 +362,9 @@ class Option(BaseOption):
                     calculation_validator(_value,
                                           _index,
                                           )
+        val = value
+        err_index = force_index
         try:
-            val = value
-            err_index = force_index
             if not self.impl_is_multi():
                 do_validation(val, None)
             elif force_index is not None:
@@ -385,8 +384,6 @@ class Option(BaseOption):
                                   )
             elif isinstance(value, Calculation) and config_bag is undefined:
                 pass
-            elif not isinstance(value, list):
-                raise ValueError(_('which must be a list'))
             elif self.impl_is_submulti():
                 for err_index, lval in enumerate(value):
                     if isinstance(lval, Calculation):
@@ -398,8 +395,10 @@ class Option(BaseOption):
                         do_validation(val,
                                             err_index)
                     _is_not_unique(lval, option_bag)
+            elif not isinstance(value, list):
+                raise ValueError(_('which must be a list'))
             else:
-                # FIXME suboptimal, not several time is whole=True!
+                # FIXME suboptimal, not several time for whole=True!
                 for err_index, val in enumerate(value):
                     do_validation(val,
                                   err_index,