diff --git a/openbis/source/java/ch/systemsx/cisd/openbis/generic/shared/dto/DeletedSampleRelationshipPE.java b/openbis/source/java/ch/systemsx/cisd/openbis/generic/shared/dto/DeletedSampleRelationshipPE.java
index 9ce620438db11b52fb54751b495f0e5aafe4e0da..0bf402f079be2838e3fb980338b6a74a70902deb 100644
--- a/openbis/source/java/ch/systemsx/cisd/openbis/generic/shared/dto/DeletedSampleRelationshipPE.java
+++ b/openbis/source/java/ch/systemsx/cisd/openbis/generic/shared/dto/DeletedSampleRelationshipPE.java
@@ -16,6 +16,8 @@
 
 package ch.systemsx.cisd.openbis.generic.shared.dto;
 
+import java.io.Serializable;
+
 import javax.persistence.Column;
 import javax.persistence.Entity;
 import javax.persistence.FetchType;
@@ -37,7 +39,7 @@ import ch.systemsx.cisd.openbis.generic.shared.dto.hibernate.SearchFieldConstant
  */
 @Entity
 @Table(name = TableNames.SAMPLE_RELATIONSHIPS_ALL_TABLE)
-public class DeletedSampleRelationshipPE
+public class DeletedSampleRelationshipPE implements Serializable
 {
     private static final long serialVersionUID = IServer.VERSION;