diff --git a/CHANGES b/CHANGES
index 373585b81ab..1874d1b1acd 100644
--- a/CHANGES
+++ b/CHANGES
@@ -1,3 +1,24 @@
+Release 4.5.1 (in development)
+==============================
+
+Dependencies
+------------
+
+Incompatible changes
+--------------------
+
+Deprecated
+----------
+
+Features added
+--------------
+
+Bugs fixed
+----------
+
+Testing
+--------
+
 Release 4.5.0 (released Mar 28, 2022)
 =====================================
 
diff --git a/sphinx/__init__.py b/sphinx/__init__.py
index 218f8fe3028..7672b33a2e1 100644
--- a/sphinx/__init__.py
+++ b/sphinx/__init__.py
@@ -19,8 +19,8 @@
 warnings.filterwarnings('ignore', "'U' mode is deprecated",
                         DeprecationWarning, module='docutils.io')
 
-__version__ = '4.5.0'
-__released__ = '4.5.0'  # used when Sphinx builds its own docs
+__version__ = '4.5.1+'
+__released__ = '4.5.1'  # used when Sphinx builds its own docs
 
 #: Version info for better programmatic use.
 #:
@@ -30,7 +30,7 @@
 #:
 #: .. versionadded:: 1.2
 #:    Before version 1.2, check the string ``sphinx.__version__``.
-version_info = (4, 5, 0, 'final', 0)
+version_info = (4, 5, 1, 'beta', 0)
 
 package_dir = path.abspath(path.dirname(__file__))