I think it would be better to use [bool_option from zc.buildout](https://github.com/buildout/buildout/blob/master/src/zc/buildout/buildout.py#L1982) here, it has error reporting etc and makes it's usage consistent. A downside would be that 'yes' doesn't work anymore. If you want that, you could copy the function and add more items to the _bool_names dictionary from there.