diff --git a/library/Director/Objects/IcingaServiceAssignment.php b/library/Director/Objects/IcingaServiceAssignment.php
index 5a0afca1..9910f7cb 100644
--- a/library/Director/Objects/IcingaServiceAssignment.php
+++ b/library/Director/Objects/IcingaServiceAssignment.php
@@ -6,6 +6,8 @@ class IcingaServiceAssignment extends IcingaObject
 {
     protected $table = 'icinga_service_assignment';
 
+    protected $keyName = 'id';
+
     protected $defaultProperties = array(
         'id'            => null,
         'service_id'    => null,