diff --git a/tiramisu/option/netmaskoption.py b/tiramisu/option/netmaskoption.py
index 58d7ffa..0e4d196 100644
--- a/tiramisu/option/netmaskoption.py
+++ b/tiramisu/option/netmaskoption.py
@@ -77,29 +77,28 @@ class NetmaskOption(StrOption):
                          warnings_only,
                          context,
                          _cidr=False):
-        # opts must be (netmask, ip) options
         if context is undefined and len(vals) != 2:
             raise ConfigError(_('ip_netmask needs an IP and a netmask'))
         if None in vals or len(vals) != 2:
             return
-        msg = None
         val_netmask, val_ip = vals
+        opt_netmask, opt_ip = opts
         ip = ip_interface('{0}/{1}'.format(val_ip, val_netmask))
-        network = ip.network
-        if ip.ip == network.network_address:
-            if not _cidr and current_opt == opts[1]:
-                msg = _('this is a network with netmask "{0}" ("{1}")')
-            else:
-                msg = _('IP "{0}" ("{1}") is the network')
-        elif ip.ip == network.broadcast_address:
-            if not _cidr and current_opt == opts[1]:
-                msg = _('this is a broadcast with netmask "{0}" ("{1}")')
-            else:
-                msg = _('IP "{0}" ("{1}") is the broadcast')
-        if msg is not None:
-            if not _cidr and current_opt == opts[1]:
-                raise ValueError(msg.format(val_netmask,
-                                            opts[0].impl_get_display_name()))
-            else:
-                raise ValueError(msg.format(val_ip,
-                                            opts[1].impl_get_display_name()))
+        if not _cidr and current_opt == opt_ip
+            if ip.ip == ip.network.network_address:
+                raise ValueError( _('this is a network with netmask "{0}" ("{1}")'
+                                    '').format(val_netmask,
+                                               opt_netmask.impl_get_display_name()))
+            elif ip.ip == ip.network.broadcast_address:
+                raise ValueError(_('this is a broadcast with netmask "{0}" ("{1}")'
+                                   '').format(val_netmask,
+                                              opt_netmask.impl_get_display_name()))
+        else:
+            if ip.ip == ip.network.network_address:
+                raise ValueError(_('IP "{0}" ("{1}") is the network'
+                                   '').format(val_ip,
+                                              opt_ip.impl_get_display_name()))
+            elif ip.ip == ip.network.broadcast_address:
+                raise ValueError(_('IP "{0}" ("{1}") is the broadcast'
+                                   '')format(val_ip,
+                                             opt_ip.impl_get_display_name()))