diff --git a/includes/project.class.inc b/includes/project.class.inc
index f07b504..604cf68 100755
--- a/includes/project.class.inc
+++ b/includes/project.class.inc
@@ -5,6 +5,12 @@
 
 // A genera Drupal Project "Project" with its meta data
 class Project extends FeedEntryContainer {
+
+  /**
+   * Contains the releases of this project.
+   *
+   * @var Release[]
+   */
   protected $releases = array();
   protected $server_key = NULL;
 
@@ -150,7 +156,7 @@ class Project extends FeedEntryContainer {
     usort($this->releases, array($this, 'compare_releases'));
   }
 
-  protected function compare_releases($a, $b) {
+  protected function compare_releases(Release $a, Release $b) {
     return $a->compare_versions($b->get_info('version'), $a->get_info('version'), 'mj');
   }