But apparently all bets are off if you happen to bring up the subject when his mother is around.
Graham Norton learned that the hard way when he asked the Rock of Ages star about the former couple's pending divorce during a taping of the U.K.'s The Graham Norton Show last week.
"My mum is here. She got upset when you dragged up my marriage. I saw her cry, Graham," Brand told Norton. "That's the reality because it's real people, Graham, that's my real mum. I have come here to promote a film and you made my mum cry. I don't see you as that sort of person, Graham."
"I don't see myself as that kind of person," the talk show host quickly replied, adding that he was merely mentioning it because Perry had appeared on his program the week before.
"What I would have done, mate, in your position is come up to me before the show and gone, 'Eh, listen, it's a bit odd your ex-missus was on last week. I might mention it, is that OK?'" Brand said. "But in all of the chatting and the research backstage, no one mentioned it."
Brand did eventually speak about the failed union, saying, "Some human beings get married and hopefully it works out for them and maybe it won't." However, the funnyman's scolding of Norton was partially edited out when the BBC show aired on Friday night.