diff --git a/uproot/version.py b/uproot/version.py
index 0bff8ca04..3713501c0 100644
--- a/uproot/version.py
+++ b/uproot/version.py
@@ -13,7 +13,7 @@
 
 import re
 
-__version__ = "1.0.0rc1"
+__version__ = "4.0.0rc1"
 version = __version__
 version_info = tuple(re.split(r"[-\.]", __version__))