Last month (May 5), Grimes and Elon Musk welcomed their first child into the world. After sharing a photo of himself holding his son, Musk seemingly joked on Twitter that the baby was called “X Æ A-12 Musk” – except, as it turns out, it wasn’t a joke.

The couple hit a bit of a snag, however, when it emerged they wouldn’t be able to register the name in California, as the state doesn’t allow legal names to contain numbers or symbols. Instead, they settled on the much more traditional, X AE A-XII. If you were still unconvinced that the name was real, a newly-released birth certificate proves otherwise.

Obtained by TMZ, the birth certificate confirms that baby boy X (first name) AE A-XII (middle name) Musk was born to Elon Reeve Musk and Claire Elise Boucher on May 4 2020 at 3:08PM.

Grimes previously explained the meaning behind the original name, X Æ A-12, on Twitter. “X, the unknown variable,” she wrote, illustrated by a crossed sword emoji. “Æ, my elven spelling of AI (love and/or artificial intelligence). A-12 = precursor to SR-17 (our favourite aircraft). No weapons, no defenses, just speed. Great in battle, but non-violent. (A= Archangel, my favourite song).” At the end, she added the cryptic words: “metal rat”.

Musk corrected her in a reply, writing: “SR-71, but yes.”

There’s still no confirmation on how the name is pronounced, although Musk enlightened fans a little about the initial name on Joe Rogan’s podcast: “It’s just X, the letter X. And then, the Æ is, like, pronounced ‘Ash’... and then, A-12. A-12 is my contribution,” referring to the Lockhead A-12 OXCART aircraft.

Neither Grimes nor Musk stated that the law was the reason they changed the name, but Grimes did respond to a question about it on Instagram, writing: “Roman numerals. Looks better TBH.”

Anyway, good luck to the kid.