diff --git a/file/lib/system/cache/builder/PermissionCacheBuilder.class.php b/file/lib/system/cache/builder/PermissionCacheBuilder.class.php
index c2402c8..7a58588 100644
--- a/file/lib/system/cache/builder/PermissionCacheBuilder.class.php
+++ b/file/lib/system/cache/builder/PermissionCacheBuilder.class.php
@@ -11,7 +11,7 @@
  * @package	be.bastelstu.chat
  * @subpackage	system.cache.builder
  */
-class PermissionCacheBuilder implements \wcf\system\cache\builder\AbstractCacheBuilder {
+class PermissionCacheBuilder extends \wcf\system\cache\builder\AbstractCacheBuilder {
 	/**
 	 * @see wcf\system\cache\AbstractCacheBuilder::rebuild()
 	 */
diff --git a/file/lib/system/cache/builder/RoomCacheBuilder.class.php b/file/lib/system/cache/builder/RoomCacheBuilder.class.php
index f08969d..3533677 100644
--- a/file/lib/system/cache/builder/RoomCacheBuilder.class.php
+++ b/file/lib/system/cache/builder/RoomCacheBuilder.class.php
@@ -10,7 +10,7 @@
  * @package	be.bastelstu.chat
  * @subpackage	system.cache.builder
  */
-class RoomCacheBuilder implements \wcf\system\cache\builder\AbstractCacheBuilder {
+class RoomCacheBuilder extends \wcf\system\cache\builder\AbstractCacheBuilder {
 	/**
 	 * @see	\wcf\system\cache\AbstractCacheBuilder::rebuild()
 	 */