Wal-Mart Stores Inc (NYSE:WMT) employees may deliver your next online order on their way home from work. The program is currently being tested in two New Jersey locations and one in Arkansas.

Participation in the program by the employees is voluntary. Wal-Mart is testing an app that matches customers’ online order delivery addresses with an employee’s driving route home, according to a blog post on Thursday from Marc Lore, president and CEO of Walmart eCommerce U.S. The objective is to cut shipping costs, speed the delivery of packages and allow workers to earn additional compensation, he wrote.

Lore was appointed in September 2016 to lead Wal-Mart’s U.S. e-commerce effort after when his company Jet.com was acquired by WMT. The pilot will include both Walmart.com and Jet.com shoppers.

The program is currently being tested in two New Jersey locations and one in Arkansas. The move is seen as a way for the retailer to catch up with Amazon.com, Inc. (NASDAQ:AMZN). Wal-Mart said its trucks already deliver packages to a retail location for store pickup and the same trucks can bring additional orders for a worker to deliver if they choose.

“The best part is this gives our own associates a way to earn extra income on their existing drive home,” Lore wrote. “Associates are fully in control of their experience. If they don’t want to participate, they don’t have to. If they choose to opt in, we’ve built technology that allows them to set preferences.”

Walmart has 4,700 stores across the U.S. and more than a million employees. The geographic distribution puts a WMT store within 10 miles of 90% of the U.S. population.

WMT stock is little changed in trading this morning. The shares have gained 15.5% so far this year, compared with AMZN stock which has increased 33% in that time.