Wal-Mart Stores Inc said it is tripling the number of U.S. stores in a pilot program that lets shoppers scan items with their iPhones and pay at self-checkout counters.

Walmart’s “Scan & Go” program will soon be in more than 200 stores, up from about 70. The pilot began near its home office in Bentonville, Arkansas in late 2012, then expanded to Atlanta.

Obviously it’s working well.