diff --git a/cache_toolbox/core.py b/cache_toolbox/core.py
index 0a28663..c8163b0 100644
--- a/cache_toolbox/core.py
+++ b/cache_toolbox/core.py
@@ -108,8 +108,14 @@ def instance_key(model, instance_or_pk):
     Returns the cache key for this (model, instance) pair.
     """
 
+    try:
+        model_name = model._meta.model_name
+    except AttributeError:
+        # Django version <1.6
+        model_name = model._meta.module_name
+
     return '%s.%s:%d' % (
         model._meta.app_label,
-        model._meta.module_name,
+        model_name,
         getattr(instance_or_pk, 'pk', instance_or_pk),
     )