Matthew Lawrence can look back on filming the 1993 comedy “Mrs. Doubtfire” with love.

The 42-year-old appeared at the first annual ’90s Con on Saturday where he spoke about the sage advice his late costar Robin Williams gave him during shooting.

Lawrence remembered how the Oscar winner warned him to “stay away” from drugs, particularly cocaine.

“He was the first adult who really let me in on his condition. Like, full-on let me in,” the “Boy Meets World” actor said.

He continued, “I mean, as bright as he was on camera — I would go visit him in his trailer to talk to him — it was painful for him. It’s really painful for him. He didn’t hide it. He talked to me about it.”

Williams died in 2014 at the age of 63 after committing suicide.

Lawrence then described the “gift” that the beloved comedian gave him: “Don’t ever do drugs. Especially cocaine.”

The former child star noted, “[Williams] was very serious. He was like, ‘You know when you come to my trailer and you see me like that?’ He’s like, ‘That’s the reason why. And now I’m fighting for the rest of my life because I spent 10 years doing something very stupid every day. Do not do it.’ I stayed away from it because of him.”

Lawrence then revealed that the “Good Will Hunting” star was the reason he scored his role of Chris Hilliard (Williams’ character’s son) in “Mrs. Doubtfire.”

While Lawrence was “a hair away” from winning the part, “there was another strong choice that everybody else wanted.”

He continued, “The studio wanted this other boy … I don’t know who it was, I was only 9 years old. But I did start to sense that something was up because there was like this little pause and little awkwardness and I was always the quiet one.”

When the two were conducting their screen test further on into the audition process, Williams Tried to push Lawrence’s chances forward by “doing something.”

“He very secretly reached behind my back and pinched me so hard,” the “brotherly Love” star said. “The studio started bawling and wept. I got the role because of that little moment over the other boy. It was all Robin Williams. ‘I know what I’m going to do to get this kid this job.’ Thank you, Rob.”

“Mrs. Doubtfire” also starred Sally Field, Mara Wilson, Pierce Brosnan, Harvey Fierstein, Robert Prosky and Lisa Jakub.