Actor Sean Penn says he's surprised at the “slow” progress of marriage equality.

Appearing on HuffPost Live, host Roy Sekoff asked Penn whether he was surprised at “how quickly the cultural zeitgeist has changed on gay marriage” since his 2009 Oscar-winning role in Milk.

“No,” Penn answered. “I'm surprised at how slowly it's changed.”

“There are a lot of things that have made extraordinary improvement and we all have to work hard to be patient about how fast you can move with certain things relative to the backlash it's going to take because the idealists will always want to take two steps ahead.”

“As my attention was drawn more to it as I went through my twenties and you have friends who are experiencing the oppression of [anti-gay attitudes] and so on, and the prejudice of it and the violence of it, the isolation of this… your first thing is to say, this has to change yesterday. So I'm glad it's changing, but not before people in this generation are gonna have children that are gonna look back at them and say, 'My parents were responsible for the suicide[s] of thirteen-year-old boys and girls.'”

“And I think the sooner we change it, the better our kids are gonna feel about us,” he added.