diff --git a/library/Director/Db.php b/library/Director/Db.php
index 0048a3e3..4672ac00 100644
--- a/library/Director/Db.php
+++ b/library/Director/Db.php
@@ -735,6 +735,9 @@ class Db extends DbConnection
         )->order('o.object_name');
 
         $res = $this->db()->fetchCol($select);
+        if (empty($res)) {
+            return array();
+        }
 
         return array_combine($res, $res);
     }