Gary Oldman would have played Sirius Black in the Harry Potter film series differently if he had read the original.

During an appearance on the podcast “Happy Sad Confused” on Thursday, the “Dark Knight” actor revealed that he would have approached the character differently if he had read JK Rowling’s books.

“I think my work in it is mediocre,” the Oscar winner explained. “Maybe I would have played it differently if I had read the books like Alan (Rickman), if I had been ahead of the curve, if I had known what was coming.”

Oldman played Harry’s godfather in 2004’s Harry Potter and the Prisoner of Azkaban and reprised the role in Harry Potter and the Order of the Phoenix. He also made cameo appearances in The Goblet of Fire and The Deathly Hallows: Part 2.

The 65-year-old joked that he was “still upset” that his character was killed off.

“They let me die too soon, and that still annoys me. We all bet: ‘It’s going to be Hagrid’ … and then you open the script and think: ‘That’s me. I’m out of here,'” he recalls.

Elsewhere in the interview, the British actor admitted that the “hardest thing he’s ever had to do on a film” was lying next to a frozen lake in a studio for the scene in Prisoner of Azkaban where Black’s soul is sucked out of his body.

“It took ages, it went slowly, and we were in one place for a week,” he recalled. “I had to just lie there for a week. Day in, day out, doing nothing. ‘I think my kidneys are getting a bit cold,’ and they put a little hot water bottle under you… Then on the third day, you say, ‘My neck is killing me,’ and they put a little pillow under you. The hardest thing I had to do was lie next to a frozen lake.”