get_next_post_link() and get_previous_post_link() return wrong posts

I’m using get_next_post_link() and get_previous_post_link() within the loop but the returned posts are not correct.

get_next_post_link() shows the previous post and get_previous_post_link() gives the current post. Below the context of these links:

$args['name'] = $postname;
$query = new WP_Query($args);

if($query->have_posts())
    {
    while ($query->have_posts())
        {
        $query->the_post();

        $id         = get_the_ID();
        $title          = get_the_title();
        $content        = get_the_content();

        $nextpost       = get_next_post_link('Next: %link');
        $previouspost   = get_previous_post_link('Prev: %link');
        }
    }