Elon Musk is setting the record straight on newborn son X Æ A-12’s name.

After his girlfriend, the singer Grimes, offered a detailed explanation Tuesday about the meaning behind their baby’s name, Musk corrected one point of her message.

She told her Twitter followers:

•X, the unknown variable ⚔️
•Æ, my elven spelling of Ai (love &/or Artificial intelligence)
•A-12 = precursor to SR-17 (our favorite aircraft). No weapons, no defenses, just speed. Great in battle, but non-violent 🤍
+
(A=Archangel, my favorite song)
(⚔️🐁 metal rat)

Early Wednesday morning, Musk agreed with the breakdown except for one small point regarding the aircraft: “SR-71, but yes,” wrote Musk, seemingly noting the Lockheed SR-71 Blackbird.

On Monday, 48-year-old Musk announced he and Grimes, 32, had welcomed their first child together.

Musk also shares five teenage sons with ex-wife Justine Wilson.