Stranger Things star Millie Bobby Brown and Sia collaborator Maddie Ziegler have already gushed to the world about being best friends, but it turns out their relationship got off to a bit of a rough start.

While making her first appearance on The Ellen DeGeneres Show today (January 9), Brown recalled the time her “inspiring” BFF invited her to a sleepover.

“She private messaged me on Twitter. I’d never been on a sleepover before and she was like, ‘Do you want to come over?’ So I’m like, ‘Sure, ok,’” Brown said. “So I go over and at three in the morning the fire alarm comes on. We all had to get rushed out of her apartment building and I’m crying because I’m like, ‘My first sleepover’s ruined!’ So, yeah, we’ve been through a lot.”

Thankfully, that doomed slumber party didn’t wreck the girls’ burgeoning friendship — Brown added that they text each other every single day. No word on whether she slips her BFF any Stranger Things spoilers, but we’d guess not. When DeGeneres pressed Brown for Season 2 intel, the actress wouldn’t budge. Much like Eleven, there are some things she just won’t talk about.