diff --git a/acme/setup.py b/acme/setup.py
index 6e5e11a00..0843288e6 100644
--- a/acme/setup.py
+++ b/acme/setup.py
@@ -4,7 +4,7 @@ from setuptools import setup
 from setuptools import find_packages
 
 
-version = '0.4.2'
+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 8ebba287a..46f4da54c 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 = '0.4.2'
+version = '0.5.0.dev0'
 
 # Please update tox.ini when modifying dependency version requirements
 install_requires = [
diff --git a/letsencrypt-auto-source/letsencrypt-auto b/letsencrypt-auto-source/letsencrypt-auto
index 8dda5f183..6dc2ed13e 100755
--- a/letsencrypt-auto-source/letsencrypt-auto
+++ b/letsencrypt-auto-source/letsencrypt-auto
@@ -19,7 +19,7 @@ XDG_DATA_HOME=${XDG_DATA_HOME:-~/.local/share}
 VENV_NAME="letsencrypt"
 VENV_PATH=${VENV_PATH:-"$XDG_DATA_HOME/$VENV_NAME"}
 VENV_BIN="$VENV_PATH/bin"
-LE_AUTO_VERSION="0.4.2"
+LE_AUTO_VERSION="0.5.0.dev0"
 
 # This script takes the same arguments as the main letsencrypt program, but it
 # additionally responds to --verbose (more output) and --debug (allow support
diff --git a/letsencrypt-compatibility-test/setup.py b/letsencrypt-compatibility-test/setup.py
index 80b8b0ed2..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 = '0.4.2'
+version = '0.5.0.dev0'
 
 install_requires = [
     'letsencrypt=={0}'.format(version),
diff --git a/letsencrypt-nginx/setup.py b/letsencrypt-nginx/setup.py
index 3c5069af7..e53bef059 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 = '0.4.2'
+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 e5d564f93..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__ = '0.4.2'
+__version__ = '0.5.0.dev0'
diff --git a/letshelp-letsencrypt/setup.py b/letshelp-letsencrypt/setup.py
index eabaf172c..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 = '0.4.2'
+version = '0.5.0.dev0'
 
 install_requires = [
     'setuptools',  # pkg_resources