Big Bang Theory 'Soft Kitty' Lullaby Now Source of Legal Woes

Turns out, this kitty’s got claws.

“Soft Kitty,” aka the lullaby that is Sheldon’s source of comfort on The Big Bang Theory, is at the center of a lawsuit against the CBS comedy recently filed by the lyricist’s daughters.

As reported by the Associated Press, Margaret Perry and Ellen Chase claim that the series is infringing on the copyright of a work by their mother, poet Edith Newlin, who died in 2004.

Newlin wrote “Warm Kitty” (“Warm kitty, soft kitty, little ball of fur; Happy kitty, sleepy kitty purr! purr! purr!”) in 1937, and Perry and Chase claim that the poem is the basis for Big Bang‘s “Soft Kitty” (“Soft kitty, warm kitty, little ball of fur; Happy kitty, sleepy kitty, purr! purr! purr!”).

“Warm Kitty” appeared in a children’s songbook in 1937. The music publisher that puts out the book tells our sister site Deadline it “properly and legally licensed the song to Warner Bros. for the TV series.”

Warner Bros. Television, which produces Big Bang, did not immediately respond to the AP’s request for comment.

“Soft Kitty” debuted on Big Bang in 2008 and has been sung on the show at least seven times since. Per the lawsuit, Chase became aware of the series’ lullaby in 2014 when a blog post talking about the tune came up while researching her mother’s history.