diff --git a/tiramisu/error.py b/tiramisu/error.py
index 6b154c1..55732b1 100644
--- a/tiramisu/error.py
+++ b/tiramisu/error.py
@@ -23,6 +23,8 @@
 #ValueError if function's parameter not correct
 #           or if not logical
 #           or if validation falied
+#           or multi must be a list
+#           or error with multi length
 #TypeError if parameter has no good type
 #AttributeError if no option or optiondescription in optiondescription (also when specified a path)
 
@@ -53,9 +55,3 @@ class PropertiesOptionError(AttributeError):
 class RequirementRecursionError(StandardError):
     "recursive error"
     pass
-
-
-class MultiTypeError(Exception):
-    """multi must be a list
-    or error with multi length"""
-    pass
diff --git a/tiramisu/value.py b/tiramisu/value.py
index c1d8477..f039e77 100644
--- a/tiramisu/value.py
+++ b/tiramisu/value.py
@@ -17,7 +17,7 @@
 # Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 #
 # ____________________________________________________________
-from tiramisu.error import MultiTypeError, ConfigError
+from tiramisu.error import ConfigError
 from tiramisu.setting import owners, multitypes
 from tiramisu.autolib import carry_out_calculation
 from tiramisu.i18n import _
@@ -49,9 +49,9 @@ class Values(object):
                     mastervalue = getattr(self.context, masterpath)
                     masterlen = len(mastervalue)
                     if len(value) > masterlen:
-                        raise MultiTypeError(_("invalid len for the slave: {0}"
-                                             " which has {1} as master").format(
-                                                 opt._name, masterpath))
+                        raise ValueError(_("invalid len for the slave: {0}"
+                                           " which has {1} as master").format(
+                                               opt._name, masterpath))
                     if len(value) < masterlen:
                         for num in range(0, masterlen - len(value)):
                             value.append(opt.getdefault_multi(), force=True)
@@ -163,26 +163,26 @@ class Values(object):
                 for slave in opt.master_slaves:
                     value_slave = self._get_value(slave)
                     if len(value_slave) > masterlen:
-                        raise MultiTypeError(_("invalid len for the slave: {0}"
-                                             " which has {1} as master").format(
-                                                 slave._name, opt._name))
+                        raise ValueError(_("invalid len for the slave: {0}"
+                                           " which has {1} as master").format(
+                                               slave._name, opt._name))
                     elif len(value_slave) < masterlen:
                         for num in range(0, masterlen - len(value_slave)):
                             value_slave.append(slave.getdefault_multi(), force=True)
 
             elif opt.get_multitype() == multitypes.slave:
                 if len(self._get_value(opt.master_slaves)) != len(value):
-                    raise MultiTypeError(_("invalid len for the slave: {0}"
-                                         " which has {1} as master").format(
-                                             opt._name, opt.master_slaves._name))
+                    raise ValueError(_("invalid len for the slave: {0}"
+                                       " which has {1} as master").format(
+                                           opt._name, opt.master_slaves._name))
             if not isinstance(value, Multi):
                 value = Multi(value, self.context, opt)
         self.setitem(opt, value)
 
     def setitem(self, opt, value):
         if type(value) == list:
-            raise MultiTypeError(_("the type of the value {0} which is multi shall "
-                                 "be Multi and not list").format(str(value)))
+            raise ValueError(_("the type of the value {0} which is multi shall "
+                               "be Multi and not list").format(str(value)))
         self.values[opt] = (self.context.cfgimpl_get_settings().getowner(), value)
 
     def __contains__(self, opt):
@@ -236,8 +236,8 @@ class Multi(list):
         """
         if not force:
             if self.opt.get_multitype() == multitypes.slave:
-                raise MultiTypeError(_("cannot append a value on a multi option {0}"
-                                     " which is a slave").format(self.opt._name))
+                raise ValueError(_("cannot append a value on a multi option {0}"
+                                   " which is a slave").format(self.opt._name))
             elif self.opt.get_multitype() == multitypes.master:
                 for slave in self.opt.get_master_slaves():
                     self.context.cfgimpl_get_values()[slave].append(
@@ -264,8 +264,8 @@ class Multi(list):
         """
         if not force:
             if self.opt.multitype == multitypes.slave:
-                raise MultiTypeError(_("cannot append a value on a multi option {0}"
-                                     " which is a slave").format(self.opt._name))
+                raise ValueError(_("cannot append a value on a multi option {0}"
+                                   " which is a slave").format(self.opt._name))
             elif self.opt.multitype == multitypes.master:
                 for slave in self.opt.get_master_slaves():
                     self.context.cfgimpl_get_values()[slave].pop(key, force=True)