Ann Oldenburg

USA TODAY

Mike Tyson knew Robin Williams, he told Howard Stern in a SiriusXM radio interview Wednesday.

And they even had the same drug dealer at one point.

The boxer/actor was talking about addiction, depression and his battle with demons. He explained to Stern, "People that deal with this situation (addiction), we know each other."

Tyson said he and Williams had been at meetings together.

Williams had struggled with abuse since the 1980s, entering rehab in 2006 and again on July 1, about a month before his August death.

Did they confide in one another?

"This is very interesting," said Tyson, adding, "When I met him and he said, "I was waiting for you. ... He started telling me about somebody I was purchasing from. I said to myself, how does he know this lowlife dealer I know? They shouldn't be in the same state. You go to every measure to get high. Everybody knows everybody."

When he heard of Williams' death, did it throw him?

"One hundred percent," said Tyson. "It's scary. ... If you have a mental illness, you're going to think about suicide. Suicide is our comfort."

Tyson said that the disease is to blame. "The reason he did that? He really killed the wrong person. It's all about killing the disease he possessed. It's not about killing yourself."

When Stern asked if it's like hearing a voice in your head, Tyson responded, "Think of it like this. Think about you're starving, you're absolutely famished. And that drug — heroin, cocaine — that's food."

Tyson also said it's a daily battle. "I'm clean now. But this is a constant fight. Eventually that dark entity's going to knock on the door."

And he said, "The fact is we're all human and it doesn't care what race you are, how rich you are, it just wants you to be miserable."