diff --git a/tailbone/views/batch/core.py b/tailbone/views/batch/core.py
index ea595e8e..5b5511da 100644
--- a/tailbone/views/batch/core.py
+++ b/tailbone/views/batch/core.py
@@ -30,7 +30,7 @@ import os
 import datetime
 import logging
 import tempfile
-from cStringIO import StringIO
+from six import StringIO
 
 import six
 import sqlalchemy as sa
diff --git a/tailbone/views/principal.py b/tailbone/views/principal.py
index dd82522b..23ad27cb 100644
--- a/tailbone/views/principal.py
+++ b/tailbone/views/principal.py
@@ -48,6 +48,10 @@ class PrincipalMasterView(MasterView):
             '/principal/{}.mako'.format(template),
         ] + super(PrincipalMasterView, self).get_fallback_templates(template, mobile=mobile)
 
+    def perm_sortkey(self, item):
+        key, value = item
+        return value['label'].lower()
+
     def find_by_perm(self):
         """
         View for finding all users who have been granted a given permission
@@ -55,9 +59,9 @@ class PrincipalMasterView(MasterView):
         permissions = copy.deepcopy(self.request.registry.settings.get('tailbone_permissions', {}))
 
         # sort groups, and permissions for each group, for UI's sake
-        sorted_perms = sorted(permissions.items(), key=lambda (k, v): v['label'].lower())
+        sorted_perms = sorted(permissions.items(), key=self.perm_sortkey)
         for key, group in sorted_perms:
-            group['perms'] = sorted(group['perms'].items(), key=lambda (k, v): v['label'].lower())
+            group['perms'] = sorted(group['perms'].items(), key=self.perm_sortkey)
 
         # group options are stable, permission options may depend on submitted group
         group_choices = [(gkey, group['label']) for gkey, group in sorted_perms]