diff --git a/tornado/__init__.py b/tornado/__init__.py
index <HASH>..<HASH> 100644
--- a/tornado/__init__.py
+++ b/tornado/__init__.py
@@ -22,5 +22,5 @@
 # is zero for an official release, positive for a development branch,
 # or negative for a release candidate or beta (after the base version
 # number has been incremented)
-version = "6.0"
-version_info = (6, 0, 0, 0)
+version = "6.1.dev1"
+version_info = (6, 1, 0, -100)
Bump master branch to <I>.dev1