diff --git a/plugins/tasklist/drivers/kolab/tasklist_kolab_driver.php b/plugins/tasklist/drivers/kolab/tasklist_kolab_driver.php
index 18a45770..c92ca553 100644
--- a/plugins/tasklist/drivers/kolab/tasklist_kolab_driver.php
+++ b/plugins/tasklist/drivers/kolab/tasklist_kolab_driver.php
@@ -598,7 +598,7 @@ class tasklist_kolab_driver extends tasklist_driver
             'title' => $record['title'],
 #            'location' => $record['location'],
             'description' => $record['description'],
-            'tags' => (array)$record['categories'],
+            'tags' => array_filter((array)$record['categories']),
             'flagged' => $record['priority'] == 1,
             'complete' => $record['status'] == 'COMPLETED' ? 1 : floatval($record['complete'] / 100),
             'parent_id' => $record['parent_id'],
diff --git a/plugins/tasklist/tasklist.php b/plugins/tasklist/tasklist.php
index 11793c74..840ee2e8 100644
--- a/plugins/tasklist/tasklist.php
+++ b/plugins/tasklist/tasklist.php
@@ -400,6 +400,11 @@ class tasklist extends rcube_plugin
             }
         }
 
+        // convert tags to array, filter out empty entries
+        if (isset($rec['tags']) && !is_array($rec['tags'])) {
+            $rec['tags'] = array_filter((array)$rec['tags']);
+        }
+
         // alarms cannot work without a date
         if ($rec['alarms'] && !$rec['date'] && !$rec['startdate'] && strpos($rec['alarms'], '@') === false)
             $rec['alarms'] = '';