diff --git a/django/oldforms/__init__.py b/django/oldforms/__init__.py
index 439bffa568..6edfd7059d 100644
--- a/django/oldforms/__init__.py
+++ b/django/oldforms/__init__.py
@@ -400,7 +400,7 @@ class TextField(FormField):
             self.member_name = member_name
 
     def isValidLength(self, data, form):
-        if data and self.maxlength and len(data.decode(settings.DEFAULT_CHARSET)) > self.maxlength:
+        if data and self.maxlength and len(smart_unicode(data)) > self.maxlength:
             raise validators.ValidationError, ungettext("Ensure your text is less than %s character.",
                 "Ensure your text is less than %s characters.", self.maxlength) % self.maxlength