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 8dfbfe90b..3014c9b09 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;