diff --git a/calendar/inc/class.calendar_ui.inc.php b/calendar/inc/class.calendar_ui.inc.php
index 54c6afa84b..b8617a22c0 100644
--- a/calendar/inc/class.calendar_ui.inc.php
+++ b/calendar/inc/class.calendar_ui.inc.php
@@ -304,7 +304,7 @@ class calendar_ui
 				if ($state == 'owner')
 				{
 					// only change the owners of the same resource-type as given in set_state[owner]
-					$set_owners = explode(',',$set_states['owner']);
+					$set_owners = is_array($set_states['owner']) ? $set_states['owner'] : explode(',',$set_states['owner']);
 					if ((string)$set_owners[0] === '0')	// set exactly the specified owners (without the 0)
 					{
 						if ($set_states['owner'] === '0,r0')	// small fix for resources
diff --git a/calendar/inc/class.calendar_uiforms.inc.php b/calendar/inc/class.calendar_uiforms.inc.php
index 3d543154e9..6302248433 100644
--- a/calendar/inc/class.calendar_uiforms.inc.php
+++ b/calendar/inc/class.calendar_uiforms.inc.php
@@ -96,10 +96,14 @@ class calendar_uiforms extends calendar_ui
 		{
 			if ($owner)	// make an owner who is no user or we have no add-rights a participant
 			{
+				if(!is_array($owner))
+				{
+					$owner = explode(',',$owner);
+				}
 				// if we come from ressources we don't need any users selected in calendar
 				if (!isset($_GET['participants']) || $_GET['participants'][0] != 'r')
 				{
-					foreach(explode(',',$owner) as $uid)
+					foreach($owner as $uid)
 					{
 						// only add users or a single ressource, not all ressources displayed by a category
 						if (is_numeric($uid) || $owner == $uid)