Add class to WP next and previous post link

Pretty basic question…

next_post_link() displays a link to the next post. It’s first paramter allows you to wrap the link in markup, like this:

next_post_link('%link');

But how do I actually add a class to the link/anchor itself? Here’s the solution:

Code to be placed in theme functions.php

add_filter('next_post_link', 'post_link_attributes');
add_filter('previous_post_link', 'post_link_attributes');

function post_link_attributes($output) {
    $injection = 'class="my-class"';
    return str_replace('<a href=', '<a '.$injection.' href=', $output);
}