Mamie Gummer and Ben Walker Mamie Gummer and Ben Walker

Meryl Streep has a new role: future mother-in-law.

The two-time Oscar winner's daughter, actress Mamie Gummer, has gotten engaged to actor Ben Walker. "He proposed [on Saturday]. He did it on one knee!" Gummer told Us Weekly. "My mom loves him!"

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The two met on a short film and have been dating for a year and a half. They also performed together in a spring 2008 Broadway production of Les Liaisions Dangereuses. Born Mary Willa, Gummer, 26, is the second of Streep's four children with her husband, sculptor Don Gummer. Mother and daughter co-starred in the 2007 drama Evening, in which Gummer played the younger version of Streep's character.