(CNN) -- That was a pretty catchy, sing-songy version of Sir Mix-A-Lot's rap hit "Baby Got Back" in Thursday night's episode of "Glee." It was also very familiar to fans of indie singer-songwriter Jonathan Coulton. As angry Coulton fans are clamoring on Twitter, Coulton arranged and recorded an eerily similar "Baby Got Back" cover. So similar, in fact, that the "Glee" version included Coulton's line "Johnny C's in trouble," replacing the lyric "Mix-A-Lot's in trouble" in the original song. Coulton said he was not informed beforehand, nor was he given any credit or compensation for having arranged the melody of the cover song. What's more, he says, Fox Broadcasting representatives told Coulton's representatives that "they're within their legal rights to do this, and that I should be happy for the exposure," he wrote on his blog, "even though they do not credit me, and have not even publicly acknowledged that it's my version -- so you know, it's kind of SECRET exposure."
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Indie artist Jonathan Coulton says 'Glee' used his cover song
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Lawyer: For a cover song, the copyright remains with the original artist, not the cover artist
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Coulton is exploring whether his actual audio was used by 'Glee'
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Many Coulton fans are expressing anger on Twitter
But @placeholder might have legal footing if the show used Coulton's audio track.
As of this writing, Sir @placeholder has not responded on his own Twitter account.