Erik Per Sullivan, who played Dewey on 'Malcolm in the Middle,' will not be returning for the revival series. Bryan Cranston says he is going to Harvard.

Erik Per Sullivan, who starred as Dewey in the early-2000s fox sitcom, is the lone original-series star that will not return to the Disney+ revival. On Wednesday, Bryan Cranston, who played the hapless dad Hal on the sitcom, explained why.

"He's really, really smart, and he's getting his master's at Harvard right now. He said, 'Oh God, no, I haven't acted since I was 9 or something. So I'm not into it.' "Never miss a story — sign up for PEOPLE's free daily newsletter to stay up-to-date on the best of what PEOPLE has to offer​​,