When the Stranger Things season 2 trailer debuted during San Diego Comic-Con, the energy in Hall H was through the roof. Not only does the return of the sci-fi horror show from the Duffer Brothers look incredible, but it was amplified to the max by the surprising use of Michael Jackson‘s iconic Halloween-themed hit “Thriller.”

Since Michael Jackson himself was always picky about letting his music be used commercially, his estate has also taken on a tough stance when it comes to licensing any of the King of Pop’s tracks for use in movies, TV shows, commercials, etc. In fact, they are so picky about how Michael Jackson’s music was used that the Stranger Things season 2 trailer was originally denied the rights to use the song, so much that there’s an alternate version of the trailer that doesn’t use the track.

Speaking with io9, Netflix series producer Shawn Levy talked about the difficult process of securing the rights to “Thriller” for use in the Stranger Things season 2 trailer:

“It was the hardest thing I’ve ever had to pull off as a producer. It’s very, very hard, for reasons I won’t go into. We were rejected repeatedly for months. A month ago, it was over. We had another trailer that was being shipped to San Diego, and it did not have that song. The [Duffer] brothers and I would watch it, and it really ate away at us, because we knew it was a good trailer, but with “Thriller” it’s next level.”

That means there’s a version of the trailer that was almost shown at San Diego Comic-Con that has a different song in it. Unfortunately, Shawn Levy didn’t reveal whether the music would have been another recognizable track or just a sample of the Stranger Things score, but it’s hard to imagine seeing that trailer without the cool mix of Michael Jackson’s spooky signature tune playing throughout. So how did Shawn Levy end up getting the rights? He doesn’t give up any specifics, but says:

“I basically decided to be a massive pain in the ass. I went back into bullheaded producer mode, and I figured out a way to work out a deal to license “Thriller.” That was a really happy day, the day that we finally pulled off that licensing arrangement.”

Not only does the music add something special to the trailer, but it’s the presence of Vincent Price’s voiceover that really brings the combination of pop music and ominous visuals to life in the best way possible. We’re just glad that Stranger Things season two wasn’t forced to go with some kind of slow, haunting cover of another popular song, because that’s a trailer trend we’re sick of right now. However, even that would have been leaps and bounds better than the awful use of an Imagine Dragons song in the teaser trailer for Murder on the Orient Express, but thankfully, someone already fixed that trailer for us.

Anyway, Stranger Things returns to Netflix for a second season on October 27, 2017.