def _validate_pillar_roots(pillar_roots):
    '''
    If the pillar_roots option has a key that is None then we will error out,
    just replace it with an empty list
    '''
    if not isinstance(pillar_roots, dict):
        log.warning('The pillar_roots parameter is not properly formatted,'
                    ' using defaults')
        return {'base': _expand_glob_path([salt.syspaths.BASE_PILLAR_ROOTS_DIR])}
    return _normalize_roots(pillar_roots)