diff --git a/acme/setup.py b/acme/setup.py
index a621b7634..5a77f8a67 100644
--- a/acme/setup.py
+++ b/acme/setup.py
@@ -4,7 +4,7 @@ from setuptools import setup
 from setuptools import find_packages
 
 
-version = '0.4.1'
+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 96a01548a..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 = '0.4.1'
+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 3290e86ec..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 = '0.4.1'
+version = '0.5.0.dev0'
 
 install_requires = [
     'letsencrypt=={0}'.format(version),
diff --git a/letsencrypt-nginx/setup.py b/letsencrypt-nginx/setup.py
index 25f4ca2c1..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 = '0.4.1'
+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 979ee3684..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__ = '0.4.1'
+__version__ = '0.5.0.dev0'
diff --git a/letshelp-letsencrypt/setup.py b/letshelp-letsencrypt/setup.py
index b361cf508..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 = '0.4.1'
+version = '0.5.0.dev0'
 
 install_requires = [
     'setuptools',  # pkg_resources