diff --git a/CHANGELOG.md b/CHANGELOG.md
index aca0c14..e125c48 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -4,7 +4,7 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](http://keepachangelog.com/)
 and this project adheres to [Semantic Versioning](http://semver.org/).
 
-## [Unreleased]
+## [0.4.0] - 21-SEP-2018
 ### Added=
 - `_render_traceback_` function added to `StateError` to improve formatting of the traceback in IPython and Jupyter
 - Add several examples demonstrating the use of ThermoState
@@ -107,7 +107,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 ### Added
 - First Release
 
-[Unreleased]: https://github.com/bryanwweber/thermostate/compare/v0.3.0...master
+[0.4.0]: https://github.com/bryanwweber/thermostate/compare/v0.3.0...v0.4.0
 [0.3.0]: https://github.com/bryanwweber/thermostate/compare/v0.2.4...v0.3.0
 [0.2.4]: https://github.com/bryanwweber/thermostate/compare/v0.2.3...v0.2.4
 [0.2.3]: https://github.com/bryanwweber/thermostate/compare/v0.2.2...v0.2.3
diff --git a/thermostate/_version.py b/thermostate/_version.py
index 75aa369..d168df1 100644
--- a/thermostate/_version.py
+++ b/thermostate/_version.py
@@ -1,4 +1,5 @@
-__version_info__ = ('0', '3', '0', '')
-__version__ = '.'.join(__version_info__[:3])
-if len(__version_info__) == 4:
-    __version__ += __version_info__[-1]
+"""The version of thermohw."""
+from typing import Tuple
+
+__version_info__: Tuple[int, int, int, str] = (0, 4, 0, '')
+__version__ = '.'.join([str(v) for v in __version_info__ if str(v)])