Facebook CEO Mark Zuckerberg said Tuesday he is unclear how many apps have improperly taken users’ information.

When asked how many times there was a third party app that needed to delete user data that was improperly transferred, Zuckerberg was unsure.

He added that if any apps are found to be “suspicious,” Facebook will audit them and decide if they are doing anything “improper” that would cause them to be banned from the platform.

He added his team will “follow up” with specific stats.

“Going forward, we’re going to take a more proactive position on this and do much more regular spot checks and other reviews of apps as well as increasing the amount of audits we do,” Zuckerberg said.