Help Editing comment-template.php

I want to insert post title within each comment (I get hundreds of comments, many are hundreds words long and it severely reduces my keyword density). So I thought I’d insert the title of the post somewhere within each comment.

I thought of replacing the “says” part which is listed after name of the commenter with “on post_title”

I’m having troubles figuring out how to deal with this part of the code:

<?php printf(__('<cite class="fn">%s</cite> <span class="says">on </span>'), get_comment_author_link()) ?>

How do I insert get_post_title there so post title is displayed after the “on ” part?