remove support for ‘Categories’ for a custom post type

How would I go about removing support for WordPress ‘Categories’ for a custom post type? I’ve created a custom taxonomy for the post type, so there is no need for the standard categories.

Oddly, I thought this would be easy to find out how to do via Google but I can’t find anything on it. Any help appreciated!

In the array of arguments to register_post_type()
there is a parameter “taxonomies”. If category is not specified there, then it shouldn’t appear with that post type.