diff --git a/setup.py b/setup.py
--- a/setup.py
+++ b/setup.py
@@ -360,7 +360,7 @@ if version:
 
     write_if_changed('mercurial/__version__.py', b''.join([
         b'# this file is autogenerated by setup.py\n'
-        b'version = "%s"\n' % versionb,
+        b'version = b"%s"\n' % versionb,
     ]))
 
 try: