diff --git a/docs/source/conf.py b/docs/source/conf.py
index 7bded36..ace94e3 100755
--- a/docs/source/conf.py
+++ b/docs/source/conf.py
@@ -66,7 +66,7 @@
 # The short X.Y version.
 version = ""
 # The full version, including alpha/beta/rc tags.
-release = "0.3.3"
+release = "0.4.0"
 
 # The language for content autogenerated by Sphinx. Refer to documentation
 # for a list of supported languages.
diff --git a/setup.cfg b/setup.cfg
index c9b532a..cc9b28e 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -1,5 +1,5 @@
 [bumpversion]
-current_version = 0.3.3
+current_version = 0.4.0
 commit = True
 tag = True
 
diff --git a/setup.py b/setup.py
index 0c91e29..abf43f8 100644
--- a/setup.py
+++ b/setup.py
@@ -9,7 +9,7 @@
 __contact__ = "ehbrecht@dkrz.de"
 __copyright__ = "Copyright 2018 United Kingdom Research and Innovation"
 __license__ = "BSD - see LICENSE file in top-level package directory"
-__version__ = "0.3.3"
+__version__ = "0.4.0"
 
 # One strategy for storing the overall version is to put it in the top-level
 # package's __init__ but Nb. __init__.py files are not needed to declare