Lena Dunham is letting it be known that she does not approve of pop star Rihanna's behavior, including her blatant marijuana use and rumored rekindled relationship with ex-boyfriend Chris Brown.

Dunham, whose career has skyrocketed in the past year with the incredible success of her hit HBO show, "Girls," took to Alec Baldwin's podcast, "Here's the Thing," to express her disappointment in the Barbados-born pop singer.

"[Fame is] an amazing thing and it's a platform that you have to take seriously," explains the 26-year-old. "Which is why sometimes, it's like. . . I used to be really into Rihanna, that pop star, and then it's like -- again, I don't want to ever throw stones from my glass house -- but I follow her on Instagram and I just think about how many little girls beyond what I could even comprehend are obsessed with Rihanna."

Dunham says that despite all of Rihanna's massive successes, she is setting a bad example for her younger fans: "You know, she left Barbados, she's had this amazing career, she's won a Grammy ... she's talented. And then she gets back together with Chris Brown and posts a million pictures of them smoking marijuana together on a bed."

Dunham, who says she learned the importance of being a role model through the popularity of her own show, revealed that Rihanna's behavior has affected her as a former fan: "It cracks my heart in half in a way that makes me feel like I'm 95 years old."

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