diff --git a/app/adminapi/logic/contract/SubcontractingContractNegotiationLogic.php b/app/adminapi/logic/contract/SubcontractingContractNegotiationLogic.php
index 240398d27..b847a6b49 100644
--- a/app/adminapi/logic/contract/SubcontractingContractNegotiationLogic.php
+++ b/app/adminapi/logic/contract/SubcontractingContractNegotiationLogic.php
@@ -133,6 +133,7 @@ class SubcontractingContractNegotiationLogic extends BaseLogic
         if (!empty($subcontractingContractNegotiation->contract->project)) {
             $subcontractingContractNegotiation->project = $subcontractingContractNegotiation->contract->project;
         }
+        unset($subcontractingContractNegotiation->contract->project);
         return $subcontractingContractNegotiation->toArray();
     }
 }
\ No newline at end of file