Fatal Error after update 1.9

Fatal error: Uncaught Error: Class “JoostBlog\WP\Comment\Inc\Hacks” not found in /var/www/html/wp-content/plugins/yoast-comment-hacks/yoast-comment-hacks.php:53 Stack trace: #0 /var/www/html/wp-admin/includes/plugin.php(2314): include_once() #1 /var/www/html/wp-admin/plugins.php(192): plugin_sandbox_scrape() #2 {main} thrown in /var/www/html/wp-content/plugins/yoast-comment-hacks/yoast-comment-hacks.php on line 53