diff --git a/src/newgrf_engine.cpp b/src/newgrf_engine.cpp
index bbad159637..82ab0b70fb 100644
--- a/src/newgrf_engine.cpp
+++ b/src/newgrf_engine.cpp
@@ -50,7 +50,7 @@ const SpriteGroup *GetWagonOverrideSpriteSet(EngineID engine, CargoID cargo, Eng
 	return nullptr;
 }
 
-void SetCustomEngineSprites(EngineID engine, uint8_t cargo, const SpriteGroup *group)
+void SetCustomEngineSprites(EngineID engine, CargoID cargo, const SpriteGroup *group)
 {
 	Engine *e = Engine::Get(engine);
 	assert(cargo < std::size(e->grf_prop.spritegroup));
diff --git a/src/newgrf_engine.h b/src/newgrf_engine.h
index bc396e7620..339be33d8a 100644
--- a/src/newgrf_engine.h
+++ b/src/newgrf_engine.h
@@ -78,7 +78,7 @@ struct VehicleSpriteSeq;
 
 void SetWagonOverrideSprites(EngineID engine, CargoID cargo, const struct SpriteGroup *group, std::span<EngineID> engine_ids);
 const SpriteGroup *GetWagonOverrideSpriteSet(EngineID engine, CargoID cargo, EngineID overriding_engine);
-void SetCustomEngineSprites(EngineID engine, uint8_t cargo, const struct SpriteGroup *group);
+void SetCustomEngineSprites(EngineID engine, CargoID cargo, const struct SpriteGroup *group);
 
 void GetCustomEngineSprite(EngineID engine, const Vehicle *v, Direction direction, EngineImageType image_type, VehicleSpriteSeq *result);
 #define GetCustomVehicleSprite(v, direction, image_type, result) GetCustomEngineSprite(v->engine_type, v, direction, image_type, result)