diff --git a/acme/setup.py b/acme/setup.py
index 9f228f4ed..8b7b040e5 100644
--- a/acme/setup.py
+++ b/acme/setup.py
@@ -4,7 +4,7 @@ from setuptools import setup
 from setuptools import find_packages
 
 
-version = '0.4.0'
+version = '0.5.0.dev0'
 
 # Please update tox.ini when modifying dependency version requirements
 install_requires = [
diff --git a/letsencrypt-apache/setup.py b/letsencrypt-apache/setup.py
index 922cd0e8e..a8e010f0e 100644
--- a/letsencrypt-apache/setup.py
+++ b/letsencrypt-apache/setup.py
@@ -4,7 +4,7 @@ from setuptools import setup
 from setuptools import find_packages
 
 
-version = '0.4.0'
+version = '0.5.0.dev0'
 
 # Please update tox.ini when modifying dependency version requirements
 install_requires = [
diff --git a/letsencrypt-compatibility-test/setup.py b/letsencrypt-compatibility-test/setup.py
index 4af0cffcc..67262ba72 100644
--- a/letsencrypt-compatibility-test/setup.py
+++ b/letsencrypt-compatibility-test/setup.py
@@ -4,7 +4,7 @@ from setuptools import setup
 from setuptools import find_packages
 
 
-version = '0.4.0'
+version = '0.5.0.dev0'
 
 install_requires = [
     'letsencrypt=={0}'.format(version),
diff --git a/letsencrypt-nginx/setup.py b/letsencrypt-nginx/setup.py
index 8aab19a57..656d6e04f 100644
--- a/letsencrypt-nginx/setup.py
+++ b/letsencrypt-nginx/setup.py
@@ -4,7 +4,7 @@ from setuptools import setup
 from setuptools import find_packages
 
 
-version = '0.4.0'
+version = '0.5.0.dev0'
 
 # Please update tox.ini when modifying dependency version requirements
 install_requires = [
diff --git a/letsencrypt/__init__.py b/letsencrypt/__init__.py
index 5e937310e..0dbeb1567 100644
--- a/letsencrypt/__init__.py
+++ b/letsencrypt/__init__.py
@@ -1,4 +1,4 @@
 """Let's Encrypt client."""
 
 # version number like 1.2.3a0, must have at least 2 parts, like 1.2
-__version__ = '0.4.0'
+__version__ = '0.5.0.dev0'
diff --git a/letshelp-letsencrypt/setup.py b/letshelp-letsencrypt/setup.py
index deaf9c9b5..fff8dcfc3 100644
--- a/letshelp-letsencrypt/setup.py
+++ b/letshelp-letsencrypt/setup.py
@@ -4,7 +4,7 @@ from setuptools import setup
 from setuptools import find_packages
 
 
-version = '0.4.0'
+version = '0.5.0.dev0'
 
 install_requires = [
     'setuptools',  # pkg_resources