This has been a long time coming, but starting today, Chrome users on Windows will only be able to install extensions from Google’s own Chrome Web Store. Google argues that this is meant to keep malicious extensions — which are often installed from third-party sites — in check.

Users who have already installed extensions from third-party sites may find that they have been disabled and cannot be re-enabled or re-installed. The only way to get them back up and running is by installing them through the Chrome Web Store (assuming the developer has made them available there).

Google first announced its plans for this move last November. At the time, it told developers who were hosting their extensions themselves to migrate to the Web Store as soon as possible. At that time, the company said that it would start enforcing this policy at the beginning of this month. But some developers weren’t quite ready yet, so the company decided to delay these changes until today.

As a result, chances are that the impact of today’s announcement will be relatively limited and that you won’t notice anything unusual. If some of your extensions stop working, though, you know why.

Developers will continue to be able to install extensions locally and businesses can also enable local installs through their Enterprise policies. In addition, users on the developer channel will also be unaffected by today’s changes.