Brown, 23, has reportedly texted Rihanna to cut down her alcohol consumption and partying, reported Contactmusic.
"Brown is very concerned she will end up dead like Amy Winehouse. He was really, really worried about her when he heard she was up drinking and partying by herself. So he just wanted to reach out to her and show a little support, you know?," a source said
Brown had sent her an SMS message telling her to cut out all that drinking, but Rihanna had not yet replied.
"He's just being a man and being responsible, making sure she's all right," he added.
Brown and Rihanna broke up in 2009 after the rapper physically assaulted her.