NEW YORK (AP) — Walmart is bringing back an app that lets shoppers skip the checkout line and pay for items themselves on their smartphone.

It first tested a version of the app, called Scan & Go, in 2013. But it discontinued it after customers said it was confusing to use. The retailer says it learned from the initial test and redesigned the app to make it easier to use.

A test of the updated Scan & Go app began this year at some stores in Houston, Orlando, Florida, and near Walmart's headquarters in Bentonville, Arkansas. The test is now being expanded to stores in Dallas and Nashville, Tennessee.

The company, Wal-Mart Stores Inc., declined to say exactly how many stores are taking part in the test.