diff --git a/CHANGELOG.md b/CHANGELOG.md
index e594d9c23d4a5d5791cd437e25fa08f953179e9a..081b3a84035642a50d4163ec926281d409b42e66 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -5,6 +5,22 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## [Unreleased]
+
+### Added ###
+
+### Changed ###
+
+### Deprecated ###
+
+### Removed ###
+
+### Fixed ###
+
+### Security ###
+
+### Documentation ###
+
 ## [0.9.0] - 2022-10-24
 (Florian Spreckelsen)
 
diff --git a/setup.py b/setup.py
index 9618cd53077e58c35cafb4611b3520b9355eead9..e044d1f587b9010d2dd3e29f99a8345d4c8c76d4 100755
--- a/setup.py
+++ b/setup.py
@@ -45,10 +45,10 @@ from setuptools import find_packages, setup
 # OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 ########################################################################
 
-ISRELEASED = True
+ISRELEASED = False
 MAJOR = 0
 MINOR = 9
-MICRO = 0
+MICRO = 1
 # Do not tag as pre-release until this commit
 # https://github.com/pypa/packaging/pull/515
 # has made it into a release. Probably we should wait for pypa/packaging>=21.4
diff --git a/src/doc/conf.py b/src/doc/conf.py
index 7f5f70a82fc2782cba18891bcb23598a93033b59..0c1cab805572aa0a548c5f674d0db531be7a0f5c 100644
--- a/src/doc/conf.py
+++ b/src/doc/conf.py
@@ -32,7 +32,7 @@ author = 'Daniel Hornung'
 version = '0.9.0'
 # The full version, including alpha/beta/rc tags
 # release = '0.5.2-rc2'
-release = '0.9.0'
+release = '0.9.1-dev'
 
 
 # -- General configuration ---------------------------------------------------