diff --git a/src/economy.cpp b/src/economy.cpp
--- a/src/economy.cpp
+++ b/src/economy.cpp
@@ -123,7 +123,7 @@ Money CalculateCompanyValue(const Compan
 
 		if (v->type == VEH_TRAIN ||
 				v->type == VEH_ROAD ||
-				(v->type == VEH_AIRCRAFT && IsNormalAircraft(v)) ||
+				(v->type == VEH_AIRCRAFT && Aircraft::From(v)->IsNormalAircraft()) ||
 				v->type == VEH_SHIP) {
 			value += v->value * 3 >> 1;
 		}
@@ -1300,7 +1300,7 @@ static void LoadUnloadVehicle(Vehicle *v
 		byte load_amount = EngInfo(v->engine_type)->load_amount;
 
 		/* The default loadamount for mail is 1/4 of the load amount for passengers */
-		if (v->type == VEH_AIRCRAFT && !IsNormalAircraft(v)) load_amount = (load_amount + 3) / 4;
+		if (v->type == VEH_AIRCRAFT && !Aircraft::From(v)->IsNormalAircraft()) load_amount = (load_amount + 3) / 4;
 
 		if (_settings_game.order.gradual_loading && HasBit(EngInfo(v->engine_type)->callbackmask, CBM_VEHICLE_LOAD_AMOUNT)) {
 			uint16 cb_load_amount = GetVehicleCallback(CBID_VEHICLE_LOAD_AMOUNT, 0, 0, v->engine_type, v);