diff --git a/CHANGES.rst b/CHANGES.rst
index 1646b35..6699198 100644
--- a/CHANGES.rst
+++ b/CHANGES.rst
@@ -1,6 +1,9 @@
 Changelog for Isso
 ==================
 
+0.12.3 (UNRELEASED)
+-------------------
+
 0.12.2 (2019-01-21)
 -------------------
 
diff --git a/setup.py b/setup.py
index 321c4a8..d2d171e 100644
--- a/setup.py
+++ b/setup.py
@@ -15,7 +15,7 @@ elif (3, 0) <= sys.version_info < (3, 4):
 
 setup(
     name='isso',
-    version='0.12.2',
+    version='0.12.3dev0',
     author='Martin Zimmermann',
     author_email='info@posativ.org',
     packages=find_packages(),