diff --git a/navalplanner-business/src/main/resources/org/navalplanner/business/workreports/entities/WorkReports.hbm.xml b/navalplanner-business/src/main/resources/org/navalplanner/business/workreports/entities/WorkReports.hbm.xml
index d5007c0f8..56b2759ed 100644
--- a/navalplanner-business/src/main/resources/org/navalplanner/business/workreports/entities/WorkReports.hbm.xml
+++ b/navalplanner-business/src/main/resources/org/navalplanner/business/workreports/entities/WorkReports.hbm.xml
@@ -47,9 +47,9 @@
 
     <many-to-one name="workReport" class="org.navalplanner.business.workreports.entities.WorkReport" column="WORK_REPORT_ID" />
 
-    <many-to-one name="resource" class="org.navalplanner.business.resources.entities.Resource" column="RESOURCE_ID" />
+    <many-to-one name="resource" class="org.navalplanner.business.resources.entities.Resource" column="RESOURCE_ID" not-null="true"/>
 
-    <many-to-one name="orderElement" class="org.navalplanner.business.orders.entities.OrderElement" column="ORDER_ELEMENT_ID" />
+    <many-to-one name="orderElement" class="org.navalplanner.business.orders.entities.OrderElement" column="ORDER_ELEMENT_ID" not-null="true"/>
 
     <set name="criterions" table="CRITERION_WORK_REPORT_LINE" inverse="false">
         <key column="WORK_REPORT_LINE_ID" not-null="false" />