diff --git a/CHANGES.txt b/CHANGES.txt
index 159cbe3..bdb938a 100644
--- a/CHANGES.txt
+++ b/CHANGES.txt
@@ -1,6 +1,12 @@
 Changes
 =======
 
+4.0.1 (unreleased)
+------------------
+
+- Nothing changed yet.
+
+
 4.0.0 (2013-02-28)
 ------------------
 
diff --git a/setup.py b/setup.py
index 4849448..b671346 100644
--- a/setup.py
+++ b/setup.py
@@ -42,7 +42,7 @@ def alltests():
 
 setup(
     name='zope.deferredimport',
-    version='4.0.0',
+    version='4.0.1.dev0',
     url='http://pypi.python.org/pypi/zope.deferredimport',
     license='ZPL 2.1',
     description=('zope.deferredimport allows you to perform imports names '