Index: django/contrib/flatpages/models.py
===================================================================
--- django/contrib/flatpages/models.py	(revision 6826)
+++ django/contrib/flatpages/models.py	(working copy)
@@ -3,6 +3,9 @@
 from django.contrib.sites.models import Site
 from django.utils.translation import ugettext_lazy as _
 
+import re
+validators.alnumurl_re = re.compile(r'^[-\w/~]+$')
+
 class FlatPage(models.Model):
     url = models.CharField(_('URL'), max_length=100, validator_list=[validators.isAlphaNumericURL], db_index=True,
         help_text=_("Example: '/about/contact/'. Make sure to have leading and trailing slashes."))