diff --git a/apps/calendar/ajax/event/edit.form.php b/apps/calendar/ajax/event/edit.form.php
index 837edbbbf05..a979836755b 100644
--- a/apps/calendar/ajax/event/edit.form.php
+++ b/apps/calendar/ajax/event/edit.form.php
@@ -41,13 +41,8 @@ switch($dtstart->getDateType()) {
 
 $summary = $vevent->getAsString('SUMMARY');
 $location = $vevent->getAsString('LOCATION');
-$categories = $vevent->getAsArray('CATEGORIES');
+$categories = $vevent->getAsString('CATEGORIES');
 $description = $vevent->getAsString('DESCRIPTION');
-foreach($categories as $category){
-	if (!in_array($category, $category_options)){
-		array_unshift($category_options, $category);
-	}
-}
 $last_modified = $vevent->__get('LAST-MODIFIED');
 if ($last_modified){
 	$lastmodified = $last_modified->getDateTime()->format('U');
@@ -189,7 +184,6 @@ if($data['repeating'] == 1){
 }
 
 $calendar_options = OC_Calendar_Calendar::allCalendars(OC_User::getUser());
-$category_options = OC_Calendar_App::getCategoryOptions();
 $repeat_options = OC_Calendar_App::getRepeatOptions();
 $repeat_end_options = OC_Calendar_App::getEndOptions();
 $repeat_month_options = OC_Calendar_App::getMonthOptions();
@@ -205,7 +199,6 @@ $tmpl = new OC_Template('calendar', 'part.editevent');
 $tmpl->assign('id', $id);
 $tmpl->assign('lastmodified', $lastmodified);
 $tmpl->assign('calendar_options', $calendar_options);
-$tmpl->assign('category_options', $category_options);
 $tmpl->assign('repeat_options', $repeat_options);
 $tmpl->assign('repeat_month_options', $repeat_month_options);
 $tmpl->assign('repeat_weekly_options', $repeat_weekly_options);
diff --git a/apps/calendar/ajax/event/new.form.php b/apps/calendar/ajax/event/new.form.php
index c19928a727e..e7d52c675de 100644
--- a/apps/calendar/ajax/event/new.form.php
+++ b/apps/calendar/ajax/event/new.form.php
@@ -32,7 +32,6 @@ $start->setTimezone(new DateTimeZone($timezone));
 $end->setTimezone(new DateTimeZone($timezone));
 
 $calendar_options = OC_Calendar_Calendar::allCalendars(OC_User::getUser());
-$category_options = OC_Calendar_App::getCategoryOptions();
 $repeat_options = OC_Calendar_App::getRepeatOptions();
 $repeat_end_options = OC_Calendar_App::getEndOptions();
 $repeat_month_options = OC_Calendar_App::getMonthOptions();
@@ -46,7 +45,6 @@ $repeat_bymonthday_options = OC_Calendar_App::getByMonthDayOptions();
 
 $tmpl = new OC_Template('calendar', 'part.newevent');
 $tmpl->assign('calendar_options', $calendar_options);
-$tmpl->assign('category_options', $category_options);
 $tmpl->assign('repeat_options', $repeat_options);
 $tmpl->assign('repeat_month_options', $repeat_month_options);
 $tmpl->assign('repeat_weekly_options', $repeat_weekly_options);
diff --git a/apps/calendar/lib/object.php b/apps/calendar/lib/object.php
index 4d4421b5c4a..dbec61c67ec 100644
--- a/apps/calendar/lib/object.php
+++ b/apps/calendar/lib/object.php
@@ -436,10 +436,6 @@ class OC_Calendar_Object{
 			$errnum++;
 		}
 
-		if(isset($request['categories']) && !is_array($request['categories'])){
-			$errors['categories'] = $l10n->t('Not an array');
-		}
-
 		$fromday = substr($request['from'], 0, 2);
 		$frommonth = substr($request['from'], 3, 2);
 		$fromyear = substr($request['from'], 6, 4);
@@ -607,7 +603,7 @@ class OC_Calendar_Object{
 	{
 		$title = $request["title"];
 		$location = $request["location"];
-		$categories = isset($request["categories"]) ? $request["categories"] : array();
+		$categories = $request["categories"];
 		$allday = isset($request["allday"]);
 		$from = $request["from"];
 		$to  = $request["to"];
@@ -781,7 +777,7 @@ class OC_Calendar_Object{
 
 		$vevent->setString('LOCATION', $location);
 		$vevent->setString('DESCRIPTION', $description);
-		$vevent->setString('CATEGORIES', join(',', $categories));
+		$vevent->setString('CATEGORIES', $categories);
 
 		/*if($repeat == "true"){
 			$vevent->RRULE = $repeat;
diff --git a/apps/calendar/templates/part.eventform.php b/apps/calendar/templates/part.eventform.php
index 130ce111b03..3830c273a73 100644
--- a/apps/calendar/templates/part.eventform.php
+++ b/apps/calendar/templates/part.eventform.php
@@ -10,7 +10,7 @@
 		<tr>
 			<th width="75px"><?php echo $l->t("Category");?>:</th>
 			<td>
-				<input id="category" name="categories" type="text" placeholder="<?php echo $l->t('Separate categories with commas'); ?>">
+				<input id="category" name="categories" type="text" placeholder="<?php echo $l->t('Separate categories with commas'); ?>" value="<?php echo isset($_['categories']) ? htmlspecialchars($_['categories']) : '' ?>">
 				<a class="action edit" onclick="$(this).tipsy('hide');OCCategories.edit();" title="<?php echo $l->t('Edit categories'); ?>"><img alt="<?php echo $l->t('Edit categories'); ?>" src="<?php echo image_path('core','actions/rename.svg')?>" class="svg action" style="width: 16px; height: 16px;"></a>
 			</td>
 			<?php if(count($_['calendar_options']) > 1) { ?>