Is there a way to tweak this to just stop guessing the URL of custom post type

I have some custom post type pages (private pages) that I don’t want people to be able to guess the URL of. Is there a way to tweak this plugin to only stop the guessing of those post types?

I tried something like:

function remove_redirect_guess_404_permalink( $redirect_url ) {
	if ( is_404() && !isset($_GET['p']) && ( 'private' == get_post_type() ) )
		return false;
	return $redirect_url;
}

add_filter( 'redirect_canonical', 'remove_redirect_guess_404_permalink' );

But it doesn’t seem to work.

Thanks!

Charles

https://www.ads-software.com/plugins/disable-url-autocorrect-guessing/