diff --git a/tests/Services/ProjectSystem/ProjectBuildHelperTest.php b/tests/Services/ProjectSystem/ProjectBuildHelperTest.php
index 53dc4b4c..94d991e7 100644
--- a/tests/Services/ProjectSystem/ProjectBuildHelperTest.php
+++ b/tests/Services/ProjectSystem/ProjectBuildHelperTest.php
@@ -225,7 +225,7 @@ final class ProjectBuildHelperTest extends WebTestCase
         $entry2 = new ProjectBOMEntry();
         $entry2->setPart(new Part());
         $entry2->setQuantity(2);
-        $subproject->setBuildPart($entry2);
+        $subproject->setBuildPart($entry2->getPart());
         $project->addBomEntry($entry2);
 
         // 4 × 1.50 + 2 x (2 x 3.5) = 20.00 for 1 build