How to set the number of posts on homepage, without affecting categories?

There was already some discussion around this topic, but without tangible solutions. I want to change the number of posts on the homepage without using the WP control panel because it will also change the posts on categories and search results.

I tried to add this line before the loop:

<?php
if (is_home()) {
query_posts(‘posts_per_page=1’);
}

It worked but it broke the “Next Page” and “Previous Page” navigation.

Any hints on how to fix that or other possible ways to limit the number of posts on homepage?