Working opposite a terrifying ancient vampire wasn’t the most disturbing part of making Nosferatu for Nicholas Hoult.

The 2x Golden Globe nominee confirmed there was a “big rat budget” for the Robert Eggers-helmed horror film, with scenes that required him to wade through upwards of 5,000 “incontinent rats.”

“I think we had like 5,000 rats,” he said on The Graham Norton Show. “Some of them were trained as well. They were all trained, and I was like, ‘You couldn’t have trained all of them.’ There were certain pockets of them that were trained.

“And they were incontinent rats, so it was kinda stinky. … I heard someone else say they were incontinent, it sounded smart. You’re right, they’re just rats. They just pee and poo anywhere. Luckily, I just had to wade through them,” added Hoult.

Hoult previously opened up to Deadline about the experience with his tiny co-stars, which also covered Count Orlok (Bill Skarsgård) during one scene of the vampire in a sarcophagus.

“I remember when I was opening the casket, and Bill’s laying in there, and there were rats in there, so he was locked in there with rats and I was like, ‘I’m going to keep getting this wrong, so he has to do it more and more,’” said Hoult. “When we first burst into that room, there were the 5,000 rats, and then they were almost like a carpet. Rat rugs. That’s what I’ll be selling on my Etsy store.”

Eggers also recalled working with the vermin on his remake of the 1922 German vampire silent film, noting, “A great deal of the rats were trained to enter on cue. I think in the scenes where we had thousands of rats, that is not that challenging. The big thing that makes it difficult is that we had to contain them for their safety with plexiglass that you don’t see on camera. And then, rats in the background become CG.”

Premiering Dec. 25 in U.S. theaters, Nosferatu stars Skarsgård as an ancient Transylvanian vampire who stalks a haunted young woman (Lily-Rose Depp) that becomes mysteriously obsessed with the creature.