In the ongoing fight between Facebook and ad blocking software, the social media giant appears to be winning. Adblock Plus (ABP), one of the leading ad blocking software companies, has struggled to create workarounds fast enough to match Facebook maneuvers, and the site’s ads have regularly slipped through ABP’s anti-ad measures.

Facebook first announced its intention to stop ad blockers by spinning it as a positive for users, saying that the site’s new feature would give users greater control over what kind of ads they saw. However, the controversial policy change sparked a tug of war between Facebook and a network of hackers in the ad blocking community. At first, the ad blockers were able to work around Facebook’s rules within two days, and the pro-ad blocking users were optimistic.

“This is an unfortunate move, because it takes a dark path against user choice,” ABP wrote in a blog post at the time. “But it’s also no reason to overreact: cat-and-mouse games in tech have been around as long as spammers have tried to circumvent spam filters.”

Now, ABP says that Facebook has made its ads virtually unrecognizable on a code level, making them difficult for ad blocking software to detect. The ad blocking company has vowed to respond, though it said it will need more time to create and test a new tool.

While ABP and the large community of hackers it has mustered may be struggling to combat Facebook’s advertising machine, the developer of the browser extension FB Purity claims they are having no problem killing Facebook ads for it’s users.