diff --git a/src/test/java/org/tests/model/family/ChildPerson.java b/src/test/java/org/tests/model/family/ChildPerson.java
index d5ead1109..a0139709c 100644
--- a/src/test/java/org/tests/model/family/ChildPerson.java
+++ b/src/test/java/org/tests/model/family/ChildPerson.java
@@ -9,6 +9,7 @@ import javax.persistence.ManyToOne;
 
 @Entity
 public class ChildPerson extends InheritablePerson {
+  private static final long serialVersionUID = 1L;
 
   private static final String PARENTS_JOIN = "join parent_person j1 on j1.identifier = ${ta}.parent_identifier "
     + "join grand_parent_person j2 on j2.identifier = j1.parent_identifier";
diff --git a/src/test/java/org/tests/model/family/GrandParentPerson.java b/src/test/java/org/tests/model/family/GrandParentPerson.java
index 2307ee3cb..4246290b6 100644
--- a/src/test/java/org/tests/model/family/GrandParentPerson.java
+++ b/src/test/java/org/tests/model/family/GrandParentPerson.java
@@ -13,7 +13,8 @@ import java.util.List;
 
 @Entity
 public class GrandParentPerson extends InheritablePerson {
-
+  private static final long serialVersionUID = 1L;
+  
   @OneToMany(mappedBy = "parent", cascade = CascadeType.ALL)
   @OrderBy("identifier")
   private List<ParentPerson> children = new ArrayList<>();
diff --git a/src/test/java/org/tests/model/family/InheritablePerson.java b/src/test/java/org/tests/model/family/InheritablePerson.java
index 7fe12c5a0..36c7fc74f 100644
--- a/src/test/java/org/tests/model/family/InheritablePerson.java
+++ b/src/test/java/org/tests/model/family/InheritablePerson.java
@@ -2,12 +2,15 @@ package org.tests.model.family;
 
 import org.tests.model.basic.EBasic;
 
+import java.io.Serializable;
+
 import javax.persistence.Id;
 import javax.persistence.ManyToOne;
 import javax.persistence.MappedSuperclass;
 
 @MappedSuperclass
-public abstract class InheritablePerson {
+public abstract class InheritablePerson implements Serializable {
+  private static final long serialVersionUID = 1L;
 
   @Id
   private Integer identifier;
diff --git a/src/test/java/org/tests/model/family/ParentPerson.java b/src/test/java/org/tests/model/family/ParentPerson.java
index 166e3c93a..97472ef7b 100644
--- a/src/test/java/org/tests/model/family/ParentPerson.java
+++ b/src/test/java/org/tests/model/family/ParentPerson.java
@@ -14,6 +14,7 @@ import java.util.List;
 
 @Entity
 public class ParentPerson extends InheritablePerson {
+  private static final long serialVersionUID = 1L;
 
   //This rather complex formulas should be built later by CustomAnnotationParser
   private static final String CHILD_PERSON_AGGREGATE_JOIN = "left join "