American Idol judge Randy Jackson. (WENN.COM)

Musician and producer Randy Jackson is set to join old pal Mariah Carey at the judge's table for the new season of American Idol.

Reports last month suggested Jackson would return to the show for his 12th season in January as a mentor to wannabes trying to impress Carey and two other judges, but now it appears he's back in the hot seat.

A source for the show tells TVLine.com, "The rumours are true."

And his former judging pal and now U.S. TV rival Simon Cowell insists Idol producers have made the right call, tweeting, "Just heard randy is back on idol. Right decision."

Speculation is rife that Nicki Minaj will join Jackson and Carey at the judge's table, but even she seems to be in the dark.

Asked about the role she might play on the show at the MTV Video Music Awards last week, the Starships hitmaker said, "I don't know yet. I really don't know. I have no comment on it."