diff --git a/include/class.ticket.php b/include/class.ticket.php
index 605758114102bcc1dfe959abec689b933a8e4fb9..cde27c4783d845c497f9166bd6cbc4bd90207d84 100644
--- a/include/class.ticket.php
+++ b/include/class.ticket.php
@@ -889,7 +889,7 @@ implements RestrictedAccess, Threadable, TemplateVariable {
         if (!isset($this->recipients)) {
             $list = new UserList();
             $list->add($this->getOwner());
-            if ($collabs = $this->getActiveCollaborators()) {
+            if ($collabs = $this->getThread()->getActiveCollaborators()) {
                 foreach ($collabs as $c)
                     $list->add($c);
             }