--- a/server/sources/__init__.py	Tue Oct 15 14:02:22 2013 +0200
+++ b/server/sources/__init__.py	Wed Aug 28 12:14:20 2013 +0200
@@ -183,7 +183,7 @@
             elif value is not None:
                 # type check
                 try:
-                    value = configuration.convert(value, optdict, optname)
+                    value = configuration._validate(value, optdict, optname)
                 except Exception as ex:
                     msg = unicode(ex) # XXX internationalization
                     raise ValidationError(eid, {role_name('config', 'subject'): msg})