diff --git a/CHANGELOG.rst b/CHANGELOG.rst
index 12c4d65..4102651 100644
--- a/CHANGELOG.rst
+++ b/CHANGELOG.rst
@@ -1,6 +1,13 @@
 Changelog
 =========
 
+.. _v2-4:
+
+2.4 - `master`_
+~~~~~~~~~~~~~~~
+
+.. note:: This version is not yet released and is under active development.
+
 .. _v2-3:
 
 2.3 - 2018-07-18
diff --git a/src/cryptography/__about__.py b/src/cryptography/__about__.py
index 935e656..8811cc2 100644
--- a/src/cryptography/__about__.py
+++ b/src/cryptography/__about__.py
@@ -14,7 +14,7 @@
                " and primitives to Python developers.")
 __uri__ = "https://github.com/pyca/cryptography"
 
-__version__ = "2.3"
+__version__ = "2.4.dev1"
 
 __author__ = "The cryptography developers"
 __email__ = "cryptography-dev@python.org"
diff --git a/vectors/cryptography_vectors/__about__.py b/vectors/cryptography_vectors/__about__.py
index 8f73dc7..4b46fbe 100644
--- a/vectors/cryptography_vectors/__about__.py
+++ b/vectors/cryptography_vectors/__about__.py
@@ -14,7 +14,7 @@
 
 __uri__ = "https://github.com/pyca/cryptography"
 
-__version__ = "2.3"
+__version__ = "2.4.dev1"
 
 __author__ = "The cryptography developers"
 __email__ = "cryptography-dev@python.org"