diff --git a/src/spriteloader/grf.hpp b/src/spriteloader/grf.hpp
--- a/src/spriteloader/grf.hpp
+++ b/src/spriteloader/grf.hpp
@@ -12,7 +12,7 @@ public:
 	/**
 	 * Load a sprite from the disk and return a sprite struct which is the same for all loaders.
 	 */
-	bool LoadSprite(SpriteLoader::Sprite *sprite, uint8 file_slot, size_t file_pos);
+	bool LoadSprite(SpriteLoader::Sprite *sprite, uint8 file_slot, size_t file_pos, SpriteType sprite_type);
 };
 
 #endif /* SPRITELOADER_GRF_HPP */