+# Aggregate serum sprites
+
+SERUM=$(filter serum/%, $(TILE_PNGS))
+SERUM_BIG=$(patsubst serum/%, serum_big/%, $(SERUM))
+
+# Big vehicles
+
+VEHICLE=$(filter vehicle_tiles/%_1.png, $(TILE_PNGS))
+VEHICLE_BIG=$(patsubst vehicle_tiles/%, vehicle_big/%, $(VEHICLE))
+