Grimes and Elon Musk welcomed thier baby boy earlier this week, and revealed that his name would be ‘X Æ A-12’.

While it’s entirely possible that this is either a bit of trolling or that X Æ A-12 is a cypher for a more conventional name (‘conventional’ in the sense that you can actually say it aloud), both parents have mentioned the name a few times on Twitter, and Grimes has even offered an explanation behind it. But if it is to be taken at face value, then there’s a bit of a snag – they won’t be able to register the name in California.

TMZ reports that while Grimes and Musk can name their kid whatever they want, the state of California does not allow legal names to contain numbers of symbols. (We’re only assuming that the baby was born in California, but given this is where both parents reside, it seems likely.) 

PEOPLE clarifies that the name isn’t exactly illegal, it just wouldn’t be accepted as valid by the state. They quote family law attorney David Glass as saying that a birth certificate filled out “with the odd numbers, dashes and symbols, it will be submitted and then rejected and they’ll be asked to submit it again”.

“In California, you can only use the ‘26 characters’ of the English language in your baby name,” Glass says. “Thus, you can’t have numbers, Roman numerals, accents, umlauts or other symbols or emojis. Although an apostrophe, for a name like ‘O’Connor,’ is acceptable... They have an opportunity to appeal the rejection of the birth certificate application but it’s unlikely that it will be granted because, again, California... has been struggling with using symbols.”

So there you have it – guess they’ll have to call him Brian or John instead.