diff --git a/mathics/version.py b/mathics/version.py
index 7f01dd50e..d24d22d6c 100644
--- a/mathics/version.py
+++ b/mathics/version.py
@@ -5,4 +5,4 @@
 # well as importing into Python. That's why there is no
 # space around "=" below.
 # fmt: off
-__version__="4.0.0"  # noqa
+__version__="4.0.1.dev0"  # noqa