sitemap adds extra newline to output (making RSS feed non validating)

After lot of debugging, I found out that when this module is enabled, all output between headers and content gets an extra empty line. For HTML this is not too bad, however strict RSS readers mark it as non valid. Currently I have disabled this module and now my feed is working again, however, I like this module so if someone could take a look on how and why the code of this module is responsible for an extra empty line and solve it, i'll be very thankful.