bootstrap.py file is updated from time to time from: http://svn.zope.org/*checkout*/zc.buildout/trunk/bootstrap/bootstrap.py or: http://svn.zope.org/*checkout*/zc.buildout/tags/RELEASE/bootstrap/bootstrap.py There is no need to fix it locally, all changes shall go upstream. Moreover buildout has ability to autoupdate itself, so local manipulations on that file might have side effects.