Error in the direct-post links

OK, just noticed that if I click on a link that takes me directly to a particular post in a thread, if the post was actually the last post on say, page 11, the link will actually take me to the first post of page 12.. just thought you guys should know, I presume its a counting from 0 instead of 1 problem in the code that figures out what page the post is on, or something similar.