Facebook CEO Mark Zuckerberg might be a brilliant entrepreneur and programmer, but he’s not too great at selecting new social media passwords.

According to Business Insider, hackers who went by the name “OurMine Team” broke into Zuckerberg’s Twitter and Pinterest accounts on Sunday evening. Turns out, the tech titan likely re-used his old LinkedIn password, which leaked in 2012 when Russian cyber-criminals hacked into the professional social network. More 117 million passwords were stolen in the breach, including Zuckerberg’s. However, he stuck with the same weak default password—“dadada”—even as LinkedIn executives urged users to switch up their security codes.

Aside from the public embarrassment factor (OurMine Team posted from Zuckerberg’s accounts to prove their access), the incident illustrates the importance of creating a different—and strong—password for each one of your social media, email, and online bank accounts. That way, if one of them is breached, the rest will stay secure. Can’t remember your many logins? Use a password manager to keep track of them all.

Another takeaway? Zuckerberg’s password, “dadada,” wasn’t very secure. Even if he hadn’t re-used his LinkedIn login information, there’s a chance that hackers could have “brute force” guessed it by combining random letters until they discovered the correct mix. While “dadada” isn’t one of 2015’s 25 worst passwords (after all, it’s no “123456” or “batman”), Zuckerberg should have followed experts’ advice and crafted an 8+ character code comprising an obscure mix of upper- and lowercase letters, numbers, and symbols. By following these rules of thumb, his password would be much more difficult for hackers to crack.

If you’ve already changed your LinkedIn password and followed the tips above, you’re likely (or at least hopefully) protected from hackers. Just remember: Don’t share your passwords with others, and avoid entering your password (or other private information) into online forms unless you're sure the website is SSL/TLS (Secure Socket Layer/Transport Layer Security) encrypted. And if all else fails, both you and Zuckerberg can always get help from this tech-savvy 11-year-old.

[h/t Business Insider]