diff --git a/CHANGES.rst b/CHANGES.rst
index 7444862..63aa770 100644
--- a/CHANGES.rst
+++ b/CHANGES.rst
@@ -3,6 +3,12 @@ Changelog
 
 For changes before version 3.0, see ``HISTORY.rst``.
 
+4.0a5 (unreleased)
+------------------
+
+- Nothing changed yet.
+
+
 4.0a4 (2017-02-01)
 ------------------
 
diff --git a/setup.py b/setup.py
index e3fbcc4..671f1a7 100644
--- a/setup.py
+++ b/setup.py
@@ -38,7 +38,7 @@
                      join('include', 'Acquisition', 'Acquisition.h')]),
     ]
 
-__version__ = '4.0a4'
+__version__ = '4.0a5.dev0'
 
 setup(name='AccessControl',
       version=__version__,