diff --git a/CHANGES.rst b/CHANGES.rst
index 8e5c212..24fe635 100644
--- a/CHANGES.rst
+++ b/CHANGES.rst
@@ -1,6 +1,12 @@
 Changelog
 =========
 
+5.1 (unreleased)
+----------------
+
+- Nothing changed yet.
+
+
 5.0 (2023-06-28)
 ----------------
 
diff --git a/setup.py b/setup.py
index 47a0d23..5dfc336 100644
--- a/setup.py
+++ b/setup.py
@@ -18,7 +18,7 @@
 
 setup(
     name='zExceptions',
-    version='5.0',
+    version='5.1.dev0',
     url='https://github.com/zopefoundation/zExceptions',
     license='ZPL 2.1',
     description="zExceptions contains common exceptions used in Zope.",