diff --git a/adminsortable/admin.py b/adminsortable/admin.py
index 6e9117e..de7d736 100644
--- a/adminsortable/admin.py
+++ b/adminsortable/admin.py
@@ -101,7 +101,7 @@ class SortableAdmin(SortableAdminBase, ModelAdmin):
         order can be changed via drag-and-drop.
         """
         opts = self.model._meta
-        has_perm = request.user.has_perm('{}.{}'.format(opts.app_label,
+        has_perm = request.user.has_perm('{0}.{1}'.format(opts.app_label,
             opts.get_change_permission()))
 
         # get sort group index from querystring if present
diff --git a/adminsortable/models.py b/adminsortable/models.py
index a076e94..49f56f6 100644
--- a/adminsortable/models.py
+++ b/adminsortable/models.py
@@ -51,7 +51,7 @@ class Sortable(models.Model):
                 sortable_foreign_keys.append(field)
         if len(sortable_foreign_keys) > 1:
             raise MultipleSortableForeignKeyException(
-                u'{} may only have one SortableForeignKey'.format(self))
+                u'{0} may only have one SortableForeignKey'.format(self))
 
     def save(self, *args, **kwargs):
         if not self.id:
diff --git a/sample_project/app/models.py b/sample_project/app/models.py
index 5e333f1..1758419 100644
--- a/sample_project/app/models.py
+++ b/sample_project/app/models.py
@@ -83,7 +83,7 @@ class GenericNote(SimpleModel, Sortable):
         pass
 
     def __unicode__(self):
-        return u'{}: {}'.format(self.title, self.content_object)
+        return u'{0}: {1}'.format(self.title, self.content_object)
 
 
 # An model registered as an inline that has a custom queryset
@@ -115,4 +115,4 @@ class Person(Sortable):
     )
 
     def __unicode__(self):
-        return '{} {}'.format(self.first_name, self.last_name)
+        return '{0} {1}'.format(self.first_name, self.last_name)