Amazon is bringing its automated checkout technology to a pair of Whole Foods stores, the company announced Wednesday, marking the latest test of the grab-and-go system in a full-size supermarket.

In a blog post, Amazon said the technology, called “Just Walk Out,” is coming to two Whole Foods locations scheduled to open in 2022. One store will be located in the Glover Park neighborhood of Washington, D.C., and the other in Sherman Oaks, California.

Amazon’s “Just Walk Out” technology allows shoppers to enter a store by scanning an app and exit without needing to stand in a checkout line. Cameras and sensors track what items shoppers select and charge them when they leave.

At the upcoming Whole Foods locations, shoppers who want to skip the checkout line enter the store by either scanning an app, inserting a credit or debit card linked to their Amazon account or placing their palm over the company’s palm-scanning payment system, called Amazon One.

Shoppers who opt out of using Amazon’s cashierless technology will only be able to ring up their items using self-checkout or at a customer service booth.

Amazon has deployed its cashierless technology across a growing number of store formats, including at several Fresh grocery stores and in its Go convenience stores. It also sells the technology to third-party retailers. Amazon launching the technology in Fresh and Whole Foods locations puts it ahead of start-ups that have developed similar systems but have largely struggled to roll them out to bigger stores due to the technical challenges.

The expansion of Amazon’s “Just Walk Out” system is likely to raise the ire of labor unions who have previously warned the technology will lead to the elimination of cashiers. Amazon argued in the blog post that the technology will allow Whole Foods employees to do other work in the stores.

“These locations will employ a comparable number of Team Members as existing Whole Foods Markets stores of similar sizes,” the company said. “With Just Walk Out-enabled Whole Foods Market stores, how Team Members in the store spend their time is simply shifting, allowing them to spend even more time interacting with customers and delivering a great shopping experience.”

Amazon has brought other high-tech changes to Whole Foods since it acquired the grocery chain in 2017 for more than $13 billion. In April, Amazon launched its palm-scanning payment system at a Seattle Whole Foods store and has since added the technology to other locations.