Previous posts link not working with custom permalinks with index.php

Hi,

I am currently using custom permalinks with index.php as I am on a Windows server. i.e. /index.php/%postname%/

Location of the blog is therefore at:
http://spencer.li/index.php/blog/

However, the previous posts link now doesn’t work as it points to:
http://spencer.li/index.php/page/2/

Changing to default permalinks works, but I prefer the more descriptive urls and don’t want to change all the internal links.

Is there a way to amend the values of previous_posts_link? Or are there any other solutions?

Thanks in advance,
Spencer.