diff --git a/navalplanner-webapp/src/main/java/org/navalplanner/web/orders/OrderModel.java b/navalplanner-webapp/src/main/java/org/navalplanner/web/orders/OrderModel.java
index 516f0449c..860e63447 100644
--- a/navalplanner-webapp/src/main/java/org/navalplanner/web/orders/OrderModel.java
+++ b/navalplanner-webapp/src/main/java/org/navalplanner/web/orders/OrderModel.java
@@ -518,6 +518,8 @@ public class OrderModel extends IntegrationEntityModel implements IOrderModel {
         dontPoseAsTransientObjectAnymore(orderElement.getTaskElements());
         dontPoseAsTransientObjectAnymore(orderElement.getHoursGroups());
         dontPoseAsTransientObjectAnymore(orderElement.getTaskQualityForms());
+        dontPoseAsTransientObjectAnymore(orderElement
+                .getAllMaterialAssignments());
 
         for (HoursGroup hoursGroup : orderElement.getHoursGroups()) {
             dontPoseAsTransientObjectAnymore(hoursGroup