diff --git a/categories/settings.py b/categories/settings.py
index 052ce53..33e7bbf 100644
--- a/categories/settings.py
+++ b/categories/settings.py
@@ -7,8 +7,8 @@ DEFAULT_SETTINGS = {
     'ALLOW_SLUG_CHANGE': False,
     'CACHE_VIEW_LENGTH': 0,
     'RELATION_MODELS': [],
-    'M2M_REGISTRY': [],
-    'FK_REGISTRY': [],
+    'M2M_REGISTRY': {},
+    'FK_REGISTRY': {},
     'THUMBNAIL_UPLOAD_PATH': 'uploads/categories/thumbnails',
     'THUMBNAIL_STORAGE': settings.DEFAULT_FILE_STORAGE,
 }