diff --git a/CHANGES.rst b/CHANGES.rst
index c41d45e..b75b708 100644
--- a/CHANGES.rst
+++ b/CHANGES.rst
@@ -2,8 +2,8 @@ Changelog
 =========
 
 
-4.0.10 (unreleased)
--------------------
+5.0.0 (unreleased)
+------------------
 
 Breaking changes:
 
diff --git a/src/icalendar/__init__.py b/src/icalendar/__init__.py
index 8664e9d..da1e056 100644
--- a/src/icalendar/__init__.py
+++ b/src/icalendar/__init__.py
@@ -1,5 +1,5 @@
 # -*- coding: utf-8 -*-
-__version__ = '4.0.10.dev0'
+__version__ = '5.0.0.dev0'
 
 from icalendar.cal import (
     Calendar,