Following this week’s Season 4 finale of Invincible, creator Robert Kirkman explained one major change from the comic books.

The Prime Video series’ showrunner, who also created the comic book source material, noted that he gender-swapped the Tech Jacket hero Zack Thompson to Zoe Thompson in order to “correct a shortcoming” from when he first created the comic in 2002.

“Tech Jacket has his own series and his own stories and is definitely a fully well-rounded character, but I think in the context of Invincible and the way we adapted the Viltrumite War storyline, if Zack were to show up, there’s not a lot that you’re gonna get from that character that you’re not getting from Oliver or Mark,” he explained to The Wrap. “There’s just a lot of similarities there.”

Kirkman added, “One of the downsides of Invincible is Cory Walker and I were like 23 and 21 when we started that book, and your default when you’re not really paying attention is yourself. Every time we introduce another character, ‘Oh look! It’s another white male! Who knew?’ It’s just a shortcoming that we hadn’t quite noticed and done our due diligence to correct.”

Voiced by Zoey Deutch (with LeVar Burton voicing the Tech Jacket’s AI), Zoe Thompson and her extraterrestrial suit of armor and weaponry arrived in the back half of Season 4, with some inspiration from Kirkman’s own daughter.

“I tell my daughter not to curse, and it doesn’t work,” he said with a laugh, referencing a similar moment between Zoe and her dad in the show.

With Invincible receiving an early Season 5 renewal last July, all episodes of Seasons 1-4 are available to stream now on Prime Video.