Facebook’s plan to stop ad blockers has already been foiled. Adblock Plus has found a way to strip ads from Facebook, even when they’re served up in Facebook’s new ad blocker-proof format. Anyone with a fully updated version of Adblock Plus should once again be able to avoid ads in Facebook’s sidebar and News Feed.

Facebook says that in its attempt to remove ads, Adblock Plus is also removing regular posts. “We’re disappointed that ad blocking companies are punishing people on Facebook as these new attempts don’t just block ads but also posts from friends and Pages,” a Facebook spokesperson said. “This isn’t a good experience for people and we plan to address the issue.”

Imperfect as it may be, the release of a new ad blocker is still bad news for Facebook, which rolled out its supposedly unblock able ads just two days ago. It’s entirely possible that Facebook has additional measures it can take to subvert ad blockers or that it expected that this type of back-and-forth battle will ensue.

But the fact that Adblock Plus responded in two days’ time doesn’t bode well; Facebook wants to display ads, but it’s hard to imagine it wants to devote resources to outsmarting a browser extension every 48 hours.