diff --git a/cirq/_version.py b/cirq/_version.py
index 1dba9a571da..3c946378f51 100644
--- a/cirq/_version.py
+++ b/cirq/_version.py
@@ -28,4 +28,4 @@
         'B) Explicitly install an older deprecated-but-compatible version '
         'of cirq (e.g. "python -m pip install cirq==0.5.*")')
 
-__version__ = "0.9.0"
+__version__ = "0.9.1"