diff --git a/calendar/inc/class.calendar_hooks.inc.php b/calendar/inc/class.calendar_hooks.inc.php
index 84bad4cb81..9f7d15cfb0 100644
--- a/calendar/inc/class.calendar_hooks.inc.php
+++ b/calendar/inc/class.calendar_hooks.inc.php
@@ -960,6 +960,13 @@ END:VALARM';
 		return false;
 	}
 
+	/**
+	 * Returns a list of custom widgets classes for etemplate2
+	 */
+	public static function widgets()
+	{
+		return array('calendar_owner_etemplate_widget');
+	}
 }
 
 // Not part of the class, since config hooks are still using the old style
diff --git a/calendar/inc/class.calendar_ui.inc.php b/calendar/inc/class.calendar_ui.inc.php
index 47dd97da26..82ac0da521 100644
--- a/calendar/inc/class.calendar_ui.inc.php
+++ b/calendar/inc/class.calendar_ui.inc.php
@@ -16,8 +16,6 @@ use EGroupware\Api\Egw;
 use EGroupware\Api\Etemplate;
 use EGroupware\Api\Framework;
 
-require_once("class.calendar_owner_etemplate_widget.inc.php");
-
 /**
  * Shared base-class of all calendar UserInterface classes
  *
diff --git a/calendar/setup/setup.inc.php b/calendar/setup/setup.inc.php
index 48c13e2ff2..97c5305354 100644
--- a/calendar/setup/setup.inc.php
+++ b/calendar/setup/setup.inc.php
@@ -46,6 +46,7 @@ $setup_info['calendar']['hooks']['acl_rights'] = 'calendar_hooks::acl_rights';
 $setup_info['calendar']['hooks']['categories'] = 'calendar_hooks::categories';
 $setup_info['calendar']['hooks']['mail_import'] = 'calendar_hooks::mail_import';
 $setup_info['calendar']['hooks']['notifications_actions'] = 'calendar_hooks::notifications_actions';
+$setup_info['calendar']['hooks']['etemplate2_register_widgets'] = 'calendar_hooks::widgets';
 
 /* Dependencies for this app to work */
 $setup_info['calendar']['depends'][] = array(