We’ve been waiting for Apple to release the M5 Pro and M5 Max MacBook Pro for weeks, sometime after the release of macOS 26.3. Well, now that the release candidates for 26.3 are available, we should see those new MacBooks next week. But there’s another bit of intrigue: based on the code inside, some light was shed on another chip we’ve all been wondering about.

According to a report by MacRumors, the iOS 26.3 release candidate includes references to the M5 Max and the M5 Ultra chips. The code doesn’t explicitly say “M5 Max” or “M5 Ultra,” but rather references model and platform codes that align with those chip families (T6051 and T6052 model numbers, with associated H17C and H17D platform names). The “17” is a reference to the M5 (H17G), while “C” and “D” refer to Max and Ultra chips, respectively. Curiously, the letter “S,” which is used for Pro chips, isn’t referenced in the code.

Assuming that Apple didn’t change the coding system, this reveal lets us know that yes, Apple is testing a Mac with an M5 Ultra chip. Apple did not release an M4 Ultra for the Mac Studio back in March 2024. Instead, the company went with an M3 Ultra, which, despite being of an older generation, is currently Apple’s fastest chip. Apple never publicly explained why it went this direction, nor why the Mac Pro stuck with the M2 Ultra.

At the time, the M3 Ultra left us wondering about the next Ultra chip: would it be an M4 or M5? Well, it looks like we now know. But what about the M5 Pro? It’s possible that Apple simply left out the reference and could add it later when the software is released. Another possibility is that Apple changed the names, and the “D” reference actually refers to the M5 Pro (which makes this whole article moot). The last possibility is that Apple is going to release an M5 Ultra MacBook Pro, which would be a first.