diff --git a/docs/changelog.rst b/docs/changelog.rst
index 83eec415..7c79d495 100644
--- a/docs/changelog.rst
+++ b/docs/changelog.rst
@@ -17,6 +17,9 @@ Release Notes
 To avail of fixes in an unreleased version, please download a ZIP file
 `directly from GitHub <https://github.com/dw/mitogen/>`_.
 
+v0.3.4.dev0
+-------------------
+
 
 v0.3.3 (2022-06-03)
 -------------------
diff --git a/mitogen/__init__.py b/mitogen/__init__.py
index 0cd434a8..1d7654d6 100644
--- a/mitogen/__init__.py
+++ b/mitogen/__init__.py
@@ -35,7 +35,7 @@ be expected. On the slave, it is built dynamically during startup.
 
 
 #: Library version as a tuple.
-__version__ = (0, 3, 3)
+__version__ = (0, 3, 4, 'dev0')
 
 
 #: This is :data:`False` in slave contexts. Previously it was used to prevent