A report in Reuters claims that Microsoft is working on technology to eliminate cashiers and checkout lines—and Amazon.com—from the retail shopping experience. The report cites six sources, a curiously specific number.

“Microsoft is developing systems that track what shoppers add to their carts,” the Reuters report notes. “Microsoft has shown sample technology to retailers from around the world and has had talks with Walmart about a potential collaboration.”

Reuters says that this move is a “nascent challenge to Amazon.com,” though it’s designed for physical retail stores and most of Amazon’s business is done online. Amazon does own Whole Foods and operates a handful of its own retail stores. But Microsoft’s system seems to threaten Amazon Go, which is a single automated store location in Seattle. Amazon plans to open more Go stores soon, however.

Microsoft’s system, of course, will likely see broader use. And given the animosity that retailers have for Amazon, it’s unlikely that the automated shopping system it uses will be adopted by any competing retailers. It’s possible that Microsoft is showing off this system now to prevent desperate retailers from considering a potential Amazon offering.

“Making its technology cheap enough so it does not eviscerate grocers’ already thin profit margins is a major challenge for Microsoft,” one source told Reuters.