--- a/Makefile	Sat Jun 24 19:38:05 2017 +0300
+++ b/Makefile	Wed Jun 28 12:20:05 2017 +0300
@@ -1,14 +1,10 @@
-all: gtfs regions-per-stop.json
+all: gtfs.zip regions-per-stop.json
 
-regions-per-stop.json: region-representatives.json regions.gmp gtfs
-	./compute-regions.py > regions-per-stop.json
-
-gtfs: gtfs.zip
-	unzip gtfs.zip -d gtfs
+regions-per-stop.json: region-representatives.json regions.gmp gtfs.zip
+	./compute-regions.py > regions-per-stop.json || rm -f regions-per-stop.json
 
 gtfs.zip:
 	wget http://data.foli.fi/gtfs/gtfs.zip
 
 clean:
 	rm -f regions-per-stop.json gtfs.zip
-	rm -rf gtfs