diff --git a/categories/__init__.py b/categories/__init__.py
index 6d8b566..f83f522 100644
--- a/categories/__init__.py
+++ b/categories/__init__.py
@@ -3,7 +3,7 @@ __version_info__ = {
     'minor': 6,
     'micro': 0,
     'releaselevel': 'beta',
-    'serial': 4
+    'serial': 5
 }
 
 def get_version():
@@ -17,6 +17,8 @@ def get_version():
 
 __version__ = get_version()
 
+registry = {}
+
 try:
     import fields