Walmart just won a patent for audio surveillance technology that measures workers’ performance, and could even listen to their conversations with customers at checkout.

The “listening to the frontend” technology, as its called, is one of many futuristic ideas Walmart has sought to patent in recent years as it competes with Amazon for domination of the retail industry.

While there’s no guarantee that Walmart will ever build this technology, the patent shows the company is thinking about using tech not just to facilitate deliveries or make its warehouses more efficient, but also to manage its workforce, which is the largest in the United States.