People have been using Amazon to compare prices since the site made its debut in 1994, but soon Amazon may kill customers’ ability to do just that in its own brick-and-mortar stores.

Amazon — which just announced the nearly $14 billion purchase of upscale grocer Whole Foods on Friday — was recently granted a patent that could be used to track customers’ web surfing in stores and interfere with where they go online.

The patent, aptly titled “Physical store online shopping control,” details a system that would prevent customers from comparing prices in Amazon stores by watching any online activity conducted over its wi-fi network, detecting any information of interest and responding by sending the shopper to a completely different web page — or even blocking internet use altogether.

The patent clearly lays out how Amazon could employ the technology, saying the e-commerce giant could interfere in “the event that requested content is determined to be associated with or potentially associated with a competitor or an item of interest.” If Amazon doesn’t like what it sees, “information may be blocked” or the customer “may be redirected to other content,” such as an Amazon webpage.

The control Amazon would have goes beyond your web browser, extending to your entire phone. In one example, Amazon says it could send you a text, push notification or email in response to what you’re looking at online.

Additionally, the technology allows Amazon to track your location in the store, potentially guiding how Amazon would respond to your browsing.

In the last year, Amazon, led by billionaire Jeff Bezos, has pushed into the real world, opening brick-and-mortar bookstores organized by data from its website and a full grocery store that simply lets you walk in and walk out without a checkout. The catch is, you need to connect to their network and download their app.

The recently patented technology may be a next step for Amazon’s mixed marketplace — or it may not be used at all.

Amazon has a historically stood up against efforts to interfere with the free and open internet. It just signed on to a July 12 protest against the FCC’s recent initiative to roll back rules that prevent private companies from favoring access to certain websites. It’s possible that Amazon filed the patent with the intent to never use it.

Amazon didn’t respond to a request for comment.