diff --git a/apps/calendar/ajax/createcalendar.php b/apps/calendar/ajax/createcalendar.php
index f8b5974f54..b719b207c7 100644
--- a/apps/calendar/ajax/createcalendar.php
+++ b/apps/calendar/ajax/createcalendar.php
@@ -12,6 +12,18 @@ require_once('../../../lib/base.php');
 OC_JSON::checkLoggedIn();
 OC_JSON::checkAppEnabled('calendar');
 
+if(trim($_POST['name']) == ''){
+	OC_JSON::error(array('message'=>'empty'));
+	exit;
+}
+$calendars = OC_Calendar_Calendar::allCalendars(OC_User::getUser());
+foreach($calendars as $cal){
+	if($cal['displayname'] == $_POST['name']){
+		OC_JSON::error(array('message'=>'namenotavailable'));
+		exit;
+	}
+}
+
 $userid = OC_User::getUser();
 $calendarid = OC_Calendar_Calendar::addCalendar($userid, $_POST['name'], 'VEVENT,VTODO,VJOURNAL', null, 0, $_POST['color']);
 OC_Calendar_Calendar::setCalendarActive($calendarid, 1);
diff --git a/apps/calendar/ajax/updatecalendar.php b/apps/calendar/ajax/updatecalendar.php
index 14f560da5a..269b7b7ca0 100644
--- a/apps/calendar/ajax/updatecalendar.php
+++ b/apps/calendar/ajax/updatecalendar.php
@@ -12,6 +12,18 @@ require_once('../../../lib/base.php');
 OC_JSON::checkLoggedIn();
 OC_JSON::checkAppEnabled('calendar');
 
+if(trim($_POST['name']) == ''){
+	OC_JSON::error(array('message'=>'empty'));
+	exit;
+}
+$calendars = OC_Calendar_Calendar::allCalendars(OC_User::getUser());
+foreach($calendars as $cal){
+	if($cal['displayname'] == $_POST['name'] && $cal['id'] != $_POST['id']){
+		OC_JSON::error(array('message'=>'namenotavailable'));
+		exit;
+	}
+}
+
 $calendarid = $_POST['id'];
 $calendar = OC_Calendar_App::getCalendar($calendarid);//access check
 OC_Calendar_Calendar::editCalendar($calendarid, $_POST['name'], null, null, null, $_POST['color']);
diff --git a/apps/calendar/js/calendar.js b/apps/calendar/js/calendar.js
index 228ea97c2d..afd1b692dd 100644
--- a/apps/calendar/js/calendar.js
+++ b/apps/calendar/js/calendar.js
@@ -429,11 +429,17 @@ Calendar={
 				}
 			},
 			submit:function(button, calendarid){
-				var displayname = $("#displayname_"+calendarid).val();
+				var displayname = $.trim($("#displayname_"+calendarid).val());
 				var active = $("#edit_active_"+calendarid+":checked").length;
 				var description = $("#description_"+calendarid).val();
 				var calendarcolor = $("#calendarcolor_"+calendarid).val();
-
+				if(displayname == ''){
+					$("#displayname_"+calendarid).css('background-color', '#FF2626');
+					$("#displayname_"+calendarid).focus(function(){
+						$("#displayname_"+calendarid).css('background-color', '#F8F8F8');
+					});
+				}
+				
 				var url;
 				if (calendarid == 'new'){
 					url = OC.filePath('calendar', 'ajax', 'createcalendar.php');
@@ -449,6 +455,11 @@ Calendar={
 							if (calendarid == 'new'){
 								$('#choosecalendar_dialog > table').append('<tr><td colspan="6"><a href="#" onclick="Calendar.UI.Calendar.newCalendar(this);"><input type="button" value="' + newcalendar + '"></a></td></tr>');
 							}
+						}else{
+							$("#displayname_"+calendarid).css('background-color', '#FF2626');
+							$("#displayname_"+calendarid).focus(function(){
+								$("#displayname_"+calendarid).css('background-color', '#F8F8F8');
+							});
 						}
 					}, 'json');
 			},
@@ -677,6 +688,9 @@ $(document).ready(function(){
 				$('#calendar_holder').fullCalendar('option', 'aspectRatio', 1.35);
 			}
 		},
+		columnFormat: {
+		    week: 'ddd d. MMM'
+		},
 		selectable: true,
 		selectHelper: true,
 		select: Calendar.UI.newEvent,