diff --git a/src/order_cmd.cpp b/src/order_cmd.cpp
index aa0f0eacc0..ccfb330dbe 100644
--- a/src/order_cmd.cpp
+++ b/src/order_cmd.cpp
@@ -1404,8 +1404,10 @@ CommandCost CmdCloneOrder(TileIndex tile, DoCommandFlag flags, uint32 p1, uint32
 			}
 
 			if (flags & DC_EXEC) {
-				/* If the destination vehicle had a OrderList, destroy it */
-				DeleteVehicleOrders(dst);
+				/* If the destination vehicle had a OrderList, destroy it.
+				 * We only reset the order indices, if the new orders are obviously different.
+				 * (We mainly do this to keep the order indices valid and in range.) */
+				DeleteVehicleOrders(dst, false, dst->GetNumOrders() != src->GetNumOrders());
 
 				dst->orders.list = src->orders.list;
 
@@ -1451,8 +1453,10 @@ CommandCost CmdCloneOrder(TileIndex tile, DoCommandFlag flags, uint32 p1, uint32
 				Order *first = NULL;
 				Order **order_dst;
 
-				/* If the destination vehicle had an order list, destroy the chain but keep the OrderList */
-				DeleteVehicleOrders(dst, true);
+				/* If the destination vehicle had an order list, destroy the chain but keep the OrderList.
+				 * We only reset the order indices, if the new orders are obviously different.
+				 * (We mainly do this to keep the order indices valid and in range.) */
+				DeleteVehicleOrders(dst, true, dst->GetNumOrders() != src->GetNumOrders());
 
 				order_dst = &first;
 				FOR_VEHICLE_ORDERS(src, order) {
@@ -1674,11 +1678,15 @@ bool Vehicle::HasDepotOrder() const
 }
 
 /**
- *
  * Delete all orders from a vehicle
- *
+ * @param v                   Vehicle whose orders to reset
+ * @param keep_orderlist      If true, do not free the order list, only empty it.
+ * @param reset_order_indices If true, reset cur_auto_order_index and cur_real_order_index
+ *                            and cancel the current full load order (if the vehicle is loading).
+ *                            If false, _you_ have to make sure the order indices are valid after
+ *                            your messing with them!
  */
-void DeleteVehicleOrders(Vehicle *v, bool keep_orderlist)
+void DeleteVehicleOrders(Vehicle *v, bool keep_orderlist, bool reset_order_indices)
 {
 	DeleteOrderWarnings(v);
 
@@ -1691,6 +1699,13 @@ void DeleteVehicleOrders(Vehicle *v, bool keep_orderlist)
 		v->orders.list->FreeChain(keep_orderlist);
 		if (!keep_orderlist) v->orders.list = NULL;
 	}
+
+	if (reset_order_indices) {
+		v->cur_auto_order_index = v->cur_real_order_index = 0;
+		if (v->current_order.IsType(OT_LOADING)) {
+			CancelLoadingDueToDeletedOrder(v);
+		}
+	}
 }
 
 /**
@@ -1927,6 +1942,7 @@ bool ProcessOrders(Vehicle *v)
 	}
 
 	/* Get the current order */
+	assert(v->cur_auto_order_index == 0 || v->cur_auto_order_index < v->GetNumOrders());
 	v->UpdateRealOrderIndex();
 
 	const Order *order = v->GetOrder(v->cur_real_order_index);
diff --git a/src/order_func.h b/src/order_func.h
index 235f9cdc95..c6ed76d23a 100644
--- a/src/order_func.h
+++ b/src/order_func.h
@@ -20,7 +20,7 @@
 void RemoveOrderFromAllVehicles(OrderType type, DestinationID destination);
 void InvalidateVehicleOrder(const Vehicle *v, int data);
 void CheckOrders(const Vehicle*);
-void DeleteVehicleOrders(Vehicle *v, bool keep_orderlist = false);
+void DeleteVehicleOrders(Vehicle *v, bool keep_orderlist = false, bool reset_order_indices = true);
 bool ProcessOrders(Vehicle *v);
 bool UpdateOrderDest(Vehicle *v, const Order *order, int conditional_depth = 0);
 VehicleOrderID ProcessConditionalOrder(const Order *order, const Vehicle *v);
diff --git a/src/saveload/afterload.cpp b/src/saveload/afterload.cpp
index 17ac9bc814..fe99e3c3e5 100644
--- a/src/saveload/afterload.cpp
+++ b/src/saveload/afterload.cpp
@@ -2564,6 +2564,9 @@ bool AfterLoadGame()
 		FOR_ALL_VEHICLES(v) {
 			if (!v->IsPrimaryVehicle()) continue;
 
+			/* Older versions are less strict with indices being in range and fix them on the fly */
+			if (v->cur_auto_order_index >= v->GetNumOrders()) v->cur_auto_order_index = 0;
+
 			v->cur_real_order_index = v->cur_auto_order_index;
 			v->UpdateRealOrderIndex();
 		}