diff --git a/version.py b/version.py
index 3ec7fb40dd..8f444396d7 100644
--- a/version.py
+++ b/version.py
@@ -4,4 +4,4 @@
 # license that can be found in the LICENSE file or at
 # https://developers.google.com/open-source/licenses/bsd
 
-__version__ = "2.2.0a1"
+__version__ = "2.2.1b0"