diff --git a/mypy/version.py b/mypy/version.py
index 57ee134ff8b8..7a022f8d3ce3 100644
--- a/mypy/version.py
+++ b/mypy/version.py
@@ -8,7 +8,7 @@
 # - Release versions have the form "1.2.3".
 # - Dev versions have the form "1.2.3+dev" (PLUS sign to conform to PEP 440).
 # - Before 1.0 we had the form "0.NNN".
-__version__ = "1.12.0"
+__version__ = "1.12.1+dev"
 base_version = __version__
 
 mypy_dir = os.path.abspath(os.path.dirname(os.path.dirname(__file__)))