diff --git a/cirq/_version.py b/cirq/_version.py
index ade9cfac055..812c4b88ece 100644
--- a/cirq/_version.py
+++ b/cirq/_version.py
@@ -29,4 +29,4 @@
         'of cirq (e.g. "python -m pip install cirq==0.5.*")'
     )
 
-__version__ = "0.11.0.dev"
+__version__ = "0.12.0.dev"