American television network CBS and other firms related to the award-winning sitcom The Big Bang Theory were sued by two women on Tuesday over the lyrics to the lullaby “Soft Kitty” often heard on the show. The heirs of Edith Newlin, a teacher from New Hampshire who published a poem about a “soft kitty” in 1933, claimed that the show had been violating their copyrights for years, the Associated Press reported.

The lawsuit said Newlin's lyrics were used in at least eight episodes of the show since March 2008 and have also been used to sell merchandise. Her daughters Ellen Newlin Chase and Margaret Chase Perry sought unspecified damages from Warner Bros, CBS, Turner Broadcasting and Fox, among other defendants.