diff --git a/ai/default/default.c b/ai/default/default.c
index cb17433e6c..2a638e3e90 100644
--- a/ai/default/default.c
+++ b/ai/default/default.c
@@ -2327,7 +2327,7 @@ static void AiStateBuildRailVeh(Player *p)
 	TileIndex tile;
 	EngineID veh;
 	int i;
-	int cargo;
+	CargoID cargo;
 	int32 cost;
 	Vehicle *v;
 	uint loco_id;
diff --git a/newgrf_engine.c b/newgrf_engine.c
index 5fd6c0189a..7f534deed2 100644
--- a/newgrf_engine.c
+++ b/newgrf_engine.c
@@ -397,7 +397,7 @@ int GetCustomEngineSprite(EngineID engine, const Vehicle* v, Direction direction
 {
 	const SpriteGroup *group;
 	const RealSpriteGroup *rsg;
-	byte cargo = GC_PURCHASE;
+	CargoID cargo = GC_PURCHASE;
 	byte loaded = 0;
 	bool in_motion = 0;
 	int totalsets, spriteset;
@@ -487,7 +487,7 @@ bool UsesWagonOverride(const Vehicle* v)
 uint16 GetCallBackResult(uint16 callback_info, EngineID engine, const Vehicle *v)
 {
 	const SpriteGroup *group;
-	byte cargo = GC_DEFAULT;
+	CargoID cargo = GC_DEFAULT;
 
 	if (v != NULL)
 		cargo = _global_cargo_id[_opt.landscape][v->cargo_type];