diff --git a/CHANGES.rst b/CHANGES.rst
index fdba4c81..55bbc84b 100644
--- a/CHANGES.rst
+++ b/CHANGES.rst
@@ -2,6 +2,12 @@
  Changes
 =========
 
+5.4.1 (unreleased)
+==================
+
+- Nothing changed yet.
+
+
 5.4.0 (2021-04-15)
 ==================
 
diff --git a/setup.py b/setup.py
index c93d0c5e..eb846c66 100644
--- a/setup.py
+++ b/setup.py
@@ -100,7 +100,7 @@ def read(*rnames):
         )
 
 setup(name='zope.interface',
-      version='5.4.0',
+      version='5.4.1.dev0',
       url='https://github.com/zopefoundation/zope.interface',
       license='ZPL 2.1',
       description='Interfaces for Python',