diff --git a/CHANGELOG.md b/CHANGELOG.md
index f4e3d890..7f8b21ad 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,7 @@
 # Changelog
 
+## 3.4.1.dev
+
 ## 3.4.0
 * Add: option [auth] cache_logins/cache_successful_logins_expiry/cache_failed_logins for caching logins
 * Improve: [auth] log used hash method and result on debug for htpasswd authentication
diff --git a/pyproject.toml b/pyproject.toml
index 3193379d..c72edc8d 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -3,7 +3,7 @@ name = "Radicale"
 # When the version is updated, a new section in the CHANGELOG.md file must be
 # added too.
 readme = "README.md"
-version = "3.4.0"
+version = "3.4.1.dev"
 authors = [{name = "Guillaume Ayoub", email = "guillaume.ayoub@kozea.fr"}, {name = "Unrud", email = "unrud@outlook.com"}, {name = "Peter Bieringer", email = "pb@bieringer.de"}]
 license = {text = "GNU GPL v3"}
 description = "CalDAV and CardDAV Server"
diff --git a/setup.py.legacy b/setup.py.legacy
index ff0a5e7d..a5068002 100644
--- a/setup.py.legacy
+++ b/setup.py.legacy
@@ -1,7 +1,7 @@
 # This file is part of Radicale - CalDAV and CardDAV server
 # Copyright © 2009-2017 Guillaume Ayoub
 # Copyright © 2017-2018 Unrud <unrud@outlook.com>
-# Copyright © 2024-2024 Peter Bieringer <pb@bieringer.de>
+# Copyright © 2024-2025 Peter Bieringer <pb@bieringer.de>
 #
 # This library is free software: you can redistribute it and/or modify
 # it under the terms of the GNU General Public License as published by
@@ -20,7 +20,7 @@ from setuptools import find_packages, setup
 
 # When the version is updated, a new section in the CHANGELOG.md file must be
 # added too.
-VERSION = "3.4.0"
+VERSION = "3.4.1.dev"
 
 with open("README.md", encoding="utf-8") as f:
     long_description = f.read()