“Barbie” director Greta Gerwig joyfully revealed one of actor Margot Robbie’s flaws in an interview on Thursday. (Watch the video below.)

“The Late Show” host Stephen Colbert pressed Gerwig on one of her own weaknesses: speechmaking. He said he felt better knowing Gerwig isn’t good at something.

“Oh!” Gerwig said. “I have something similar with Margot Robbie... She’s so wonderful at everything she does. You can literally tell her not to cry out of one eye and she can. She’s that kind of a person. And she’s astonishingly beautiful.”

“My favorite thing about her,” Gerwig continued, “is that she... can’t sing that well.”

That sparked audience laughter and a, “wow, wow” from Colbert.

Gerwig said she asked Robbie to “belt out” the Indigo Girls’ “Closer To Fine” while shooting a scene for “Barbie.”

“She was like, ‘No, don’t make me do it.’ And I was like, ‘I love this. I love it so much. I want it to be loud,’” the director gushed.

Gerwig said she instructed the sound mix editors to “really make [Robbie] out of pitch.”

Fast-forward to 5:55:

Robbie may not have needed much help. Fast-forward to 1:14 to see her belt out the tune: