Users of the popular web browser Firefox recently discovered their browser contained an add-on called “Looking Glass” that they did not install, causing confusion as to how the add-on go there.

The extension, Looking Glass 1.0.3, added to the suspicion of Firefox users thanks to the ominous and confusing description it bears, which states simply, “MY REALITY IS JUST DIFFERENT FROM YOURS.”

As it turns out, the add-on is nothing malicious. In fact, it’s from Mozilla, the creators of the Firefox browser. Its installation in users’ browsers is part of an advertising campaign meant to promote the television program “Mr. Robot”—a show on the USA Network that follows a cybersecurity expert turned vigilante hacker.

The add-on appears to be part of a promotional game designed to satiate the “Mr. Robot” fandom until the show returns for its fourth season. From the details of the extension, Looking Glass is an augmented reality game that will take place within a user’s browser.

There may well be crossover between those who count themselves among the fans of “Mr. Robot” and those who use Mozilla’s Firefox browser—especially since the release of Firefox Quantum, which has been lauded for its privacy tools—but there are fewer sure-fire ways to irritate the privacy-minded than to install something without their permission.

As a result of the promotion, users have been taking out their frustration with Mozilla online.

“This pissed me off. Really pissed me off,” one Firefox user wrote in the Firefox community on Reddit. “Whoever was in charge of putting this weird ass extension with no real description or anything can fuck right off. Go work at Google or something.”

“I've never seen an extension in Firefox that I didn't personally add, and now all of the sudden there's a new extension that was installed with no notification and a weird fuckin' spyware sounding name and description,” another wrote .

Users have theorized that the Looking Glass extension has appeared for those who chose not to opt out of Mozilla’s Shield studies, which allow users to try out new features before they are widely available in exchange for sending data back to Mozilla to help the company tune features and make sure they run efficiently. The installation of an add-on without user permission can be viewed as an abuse of user trust.

How To Remove Looking Glass From Firefox

First, it’s important to note that even though the Looking Glass add-on is installed on a user’s browser, it is not active by default. Users have to opt in to the game for the add-on to actually activate, otherwise it sits dormant and does nothing.

Still, for users who don’t want any part of the extension, it’s possible to remove it from the browser entirely.

To do so, open Firefox, click the Tools menu and select “Add-ons.” It is also possible to access the add-ons menu by typing “about:addons” in the URL bar.

Once in the add-ons menu, click the “Extensions” option from the menu on the left-hand side. This will display all extensions that have been installed on the device, including the Looking Glass add-on.

To the right of the extension name, there should be two options: “Disable” and “Remove.” Select the “Remove” option to delete the extension in its entirety.