Google today announced Chrome extensions not in the Chrome Web Store are now blocked for all Windows users. The company says it will expand this policy to Mac users in July 2015.

Google says its decision stems from a desire to protect Chrome users — by ensuring extensions can be installed only if they’re hosted on the Chrome Web Store, the company can limit the spread of malicious extensions. The policy changes were actually first announced in November 2013, and were supposed to go into effect in January 2014. After developers requested more time, extensions started being blocked in May 2014.

Today, Google says it has seen a 75 percent drop in customer support help requests for uninstalling unwanted extensions. Yet the company isn’t satisfied with that, and it explains that not enforcing the policy on the Windows developer channel ultimately led to more problems:

Unfortunately, we’ve since observed malicious software forcing users into the developer channel in order to install unwanted off-store extensions. Affected users are left with malicious extensions running on a Chrome channel they did not choose.

That’s why the company is now enforcing the policy on all Windows channels. Bringing the same policy to Mac seems like a natural extension, no pun intended. That said, developers can still install extensions via inline installation, and businesses can continue to use enterprise policy.

Ever since Google made its intentions for the Chrome Web Store clear, critics have complained that the move only turns Chrome into a walled garden. Yet the company insists these changes are all about security: “It is crucial that our users stay safe from the reaches of malicious software developers.” That’s certainly true, as letting Chrome users “enjoy all the web has to offer without the need to worry as they browse” simply leads to a better experience, but it also ensures Google can kill extensions it simply doesn’t like.

We’ve reached out to Google regarding whether today’s news affects Chrome Canary, as the company said “all channels” but only mentioned the developer channel specifically, and whether there are plans to expand to Linux as well. We’ll update this article if we learn more.

Update: Chrome Canary is indeed included in this policy change, both for Windows and Mac. As for Linux, Google doesn’t have plans to expand the policy there, at least not yet.