diff --git a/jsprit-core/src/main/java/jsprit/core/problem/job/Delivery.java b/jsprit-core/src/main/java/jsprit/core/problem/job/Delivery.java
index cad46ce9..79532708 100644
--- a/jsprit-core/src/main/java/jsprit/core/problem/job/Delivery.java
+++ b/jsprit-core/src/main/java/jsprit/core/problem/job/Delivery.java
@@ -17,7 +17,7 @@
 package jsprit.core.problem.job;
 
 
-public final class Delivery extends Service{
+public class Delivery extends Service{
 	
 	public static class Builder extends Service.Builder {
 
diff --git a/jsprit-core/src/main/java/jsprit/core/problem/job/Pickup.java b/jsprit-core/src/main/java/jsprit/core/problem/job/Pickup.java
index 96faa6b4..e706d27f 100644
--- a/jsprit-core/src/main/java/jsprit/core/problem/job/Pickup.java
+++ b/jsprit-core/src/main/java/jsprit/core/problem/job/Pickup.java
@@ -16,7 +16,7 @@
  ******************************************************************************/
 package jsprit.core.problem.job;
 
-public final class Pickup extends Service {
+public class Pickup extends Service {
 
 	public static class Builder extends Service.Builder {