Index: django/newforms/fields.py
===================================================================
--- django/newforms/fields.py	(revision 4454)
+++ django/newforms/fields.py	(working copy)
@@ -354,7 +354,7 @@
         value = smart_unicode(value)
         if value == u'':
             return value
-        valid_values = set([str(k) for k, v in self.choices])
+        valid_values = set([smart_unicode(k) for k, v in self.choices])
         if value not in valid_values:
             raise ValidationError(gettext(u'Select a valid choice. %s is not one of the available choices.') % value)
         return value