diff --git a/setup.py b/setup.py
--- a/setup.py
+++ b/setup.py
@@ -6,7 +6,7 @@
 # './setup.py --help' for more options
 
 import sys
-if not hasattr(sys, 'version_info') or sys.version_info < (2, 3):
+if not hasattr(sys, 'version_info') or sys.version_info < (2, 3, 0, 'final'):
     raise SystemExit, "Mercurial requires python 2.3 or later."
 
 import os