Over two days of questioning in Congress, Facebook CEO Mark Zuckerberg chief revealed that he didn’t know key details of a 2011 consent decree with the Federal Trade Commission that requires Facebook to protect user privacy.

With congressional hearings over and no immediate momentum behind calls for regulation, the biggest hammer still hanging over Facebook in the U.S. is a fresh FTC investigation . The probe follows revelations that pro-Trump data-mining firm Cambridge Analytica acquired data from the profiles of millions of Facebook users. Facebook also faces inquiries in Europe.

The 2011 agreement bound Facebook to a 20-year privacy commitment , and any violations of that pact could cost Facebook a ton of money, even by its flush-with-cash standards. If Zuckerberg’s testimony before Congress is any indication, the company might have something to worry about.

Zuckerberg repeatedly assured lawmakers Tuesday and Wednesday that he believed Facebook is in compliance with that 2011 agreement. But he also flubbed simple factual questions about the consent decree.

“Congresswoman, I don’t remember if we had a financial penalty,” Zuckerberg said under questioning by Colorado Rep. Diana DeGette on Wednesday.

“You’re the CEO of the company, you entered into a consent decree and you don’t remember if you had a financial penalty?” she asked. She then pointed out that the FTC doesn’t have the authority to issue fines for first-time violations.

In response to questioning by Rep. Mike Doyle of Pennsylvania, Zuckerberg acknowledged: “I’m not familiar with all of the things the FTC said.”

Zuckerberg also faced several questions from lawmakers about how long it takes for Facebook to delete user data from its systems. He didn’t know.

The 2011 consent decree capped years of Facebook privacy mishaps, many of which revolved around its early attempts to follow users and their friends around the web. Any violations of the 2011 agreement could subject Facebook to fines of $41,484 per violation per user per day. To put that in context, Facebook could theoretically owe $8 billion for one single day of a violation affecting all of its American users.

The current FTC investigation will look at whether Facebook engaged in “unfair acts” that cause “substantial injury” to consumers.