diff --git a/src/Core/Model/Message/StateTransitionMessage.php b/src/Core/Model/Message/StateTransitionMessage.php
index d24830d0a2..4868661818 100644
--- a/src/Core/Model/Message/StateTransitionMessage.php
+++ b/src/Core/Model/Message/StateTransitionMessage.php
@@ -5,6 +5,8 @@
 
 namespace Commercetools\Core\Model\Message;
 
+use Commercetools\Core\Model\State\StateReference;
+
 abstract class StateTransitionMessage extends Message
 {
     public function fieldDefinitions()