diff --git a/nag/lib/Api.php b/nag/lib/Api.php
index a0232adac6f..3bda6b73159 100644
--- a/nag/lib/Api.php
+++ b/nag/lib/Api.php
@@ -1231,6 +1231,7 @@ public function replace($uid, $content, $contentType)
             $task = new Nag_Task();
             $task->fromASTask($content);
             $task->owner = $owner;
+            $task->uid = $uid;
             $factory->create($existing->tasklist)->modify($taskId, $task->toHash());
             break;
         default:
diff --git a/nag/lib/Task.php b/nag/lib/Task.php
index ba9a94e1c38..1778af0a850 100644
--- a/nag/lib/Task.php
+++ b/nag/lib/Task.php
@@ -272,7 +272,7 @@ class Nag_Task
     /**
      * Task tags (lazy loaded).
      *
-     * @var array
+     * @var string
      */
     protected $_tags;
 
@@ -946,7 +946,7 @@ public function synchronizeTags(array $tags)
                     'task'
                 );
             }
-            $this->_tags = $this->internaltags;
+            $this->_tags = implode(',', $this->internaltags);
         } else {
             $this->_tags = $tags;
         }
@@ -1589,7 +1589,7 @@ public function fromASTask(Horde_ActiveSync_Message_Task $message)
 
         /* Categories */
         if (is_array($message->categories) && count($message->categories)) {
-            $this->tags = $message->categories;
+            $this->tags = implode(',', $message->categories);
         }
     }