diff --git a/src/main/java/org/springframework/samples/petclinic/model/BaseEntity.java b/src/main/java/org/springframework/samples/petclinic/model/BaseEntity.java
index 8dfbfe9..3014c9b 100644
--- a/src/main/java/org/springframework/samples/petclinic/model/BaseEntity.java
+++ b/src/main/java/org/springframework/samples/petclinic/model/BaseEntity.java
@@ -27,7 +27,7 @@ import javax.persistence.MappedSuperclass;
* @author Juergen Hoeller
*/
@MappedSuperclass
-public class BaseEntity {
+public class BaseEntity implements Serializable {
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
protected Integer id;