diff --git a/constance/admin.py b/constance/admin.py
index 6187193..862759a 100644
--- a/constance/admin.py
+++ b/constance/admin.py
@@ -169,6 +169,7 @@ class Config:
         verbose_name_plural = _('config')
         abstract = False
         swapped = False
+        is_composite_pk = False
 
         def get_ordered_objects(self):
             return False