diff --git a/jsprit-core/src/main/java/jsprit/core/problem/VehicleRoutingProblem.java b/jsprit-core/src/main/java/jsprit/core/problem/VehicleRoutingProblem.java
index 95c6d62b..7a29b094 100644
--- a/jsprit-core/src/main/java/jsprit/core/problem/VehicleRoutingProblem.java
+++ b/jsprit-core/src/main/java/jsprit/core/problem/VehicleRoutingProblem.java
@@ -388,7 +388,7 @@ public class VehicleRoutingProblem {
 				Vehicle penVehicle = VehicleImpl.Builder.newInstance(vehicleId).setEarliestStart(v.getEarliestDeparture())
 						.setLatestArrival(v.getLatestArrival()).setLocationCoord(v.getCoord()).setLocationId(v.getLocationId())
 						.setReturnToDepot(v.isReturnToDepot()).setType(penType).build();
-				vehicles.add(penVehicle);
+				addVehicle(penVehicle);
 			}
 		}