Facebook declared war on the ad blockers a couple days ago, and the ad blockers have already struck back.
Adblock Plus announced Thursday that the open-source community behind the EasyList filtering mechanism—used by Adblock Plus and others—had already updated the tool to beat Facebook’s tactics.
Facebook (FB) essentially changed the way it encodes the ads on its website, supposedly so that ad blockers would no longer be able to easily identify them as ads and therefore block them. The company said it was protecting a valuable revenue stream—desktop ads are worth around $1 billion a quarter to Facebook.
Get Data Sheet, Fortune’s technology newsletter.
However, a new filter that Adblock Plus described in its Thursday blog post will apparent make the blocking work as normal again. Users can manually add its code to their filter lists, or wait for the lists to be updated automatically in the next couple days.
“The filter lists that ‘tell’ Adblock Plus what to block are in fact the product of a global community of web citizens. This time that community seems to have gotten the better of even a giant like Facebook,” wrote Adblock Plus spokesman Ben Williams.
“This sort of back-and-forth battle between the open source ad-blocking community and circumventers has been going on since ad blocking was invented, so it’s very possible that Facebook will write some code that will render the filter useless—at any time,” he added. “If that happens, the ad-blocking community will likely find another workaround, then Facebook might circumvent again, etc.”
However, Facebook said the update blocked not only ads, but Facebook pages and posts from friends.
“This isn’t a good experience for people and we plan to address the issue,” a spokesman said. “Ad blockers are a blunt instrument, which is why we’ve instead focused on building tools like ad preferences to put control in people’s hands.”
For more on Facebook’s ad-blocker-blocking, watch:
When Facebook decided to try forcing its ads past the blockers, it did indeed say it was giving users more controls over the ads they see. This includes allowing people to opt out of seeing ads from companies that are trying to target them on Facebook because they’re already on those companies’ marketing lists.
CNIL had told Facebook it was breaking French data protection law by, among other things, not giving users enough control over how they are profiled by the social network and its commercial partners. According to Le Monde, Facebook has now presented its defense and the regulator is examining it.
This article was updated with Facebook’s statement.