diff --git a/django_pandas/utils.py b/django_pandas/utils.py
index <HASH>..<HASH> 100644
--- a/django_pandas/utils.py
+++ b/django_pandas/utils.py
@@ -11,7 +11,7 @@ def replace_from_choices(choices):
 
 
 def get_base_cache_key(model):
-    return 'pandas_%s_%s_%%d_rendering' % (
+    return 'pandas_%s_%s_%%s_rendering' % (
         model._meta.app_label, model._meta.module_name)
The primary key of a model can be a string --> changed syntax for base_cache_key