Elon Musk may soon be a daddy again.

Tesla’s billionaire boss — who has already fathered twins and a set of triplets by a previous marriage — on Friday sent a cryptic tweet to his girlfriend Grimes after the electronic musician revealed she’s pregnant.

“x is y,” Musk tweeted in response to two photos showing Grimes’ baby bump draped in a black and white robe.

The “Oblivion” artist, real name Claire Boucher, announced her pregnancy on social media Wednesday with a topless photo showing a fetus superimposed onto her belly.

Boucher has not confirmed that Musk is the father. But the two have been dating since at least May 2018, when they stepped out together at that year’s Met Gala.

The meaning of the Tesla CEO’s Twitter message is unclear, but it could be an allusion to the chromosomes that determine the baby’s sex.

Boucher replied to the billionaire tech tycoon by saying “Toss a coin to ur Witcher,” an apparent reference to the Netflix series “The Witcher,” which depicts a monster hunter.

Musk may have dropped another hint about his potential fatherhood in a Thursday morning tweet. He used a baby emoji in his reply to a Twitter user who added a Grimes song to a video of Musk dancing onstage at a Tesla event in China this week.

Boucher’s announcement caused a stir online because her nipples were showing in one of her bare-chested pregnancy photos.

“The photo is so much less feral without the nipples,” she wrote in a comment on a since-deleted Instagram post with the picture. “Plus being knocked up is a very feral & war-like state of being. Might as well be what it is.”

Boucher replaced the photo with a censored version on Instagram but the original is still up on her Twitter page.