'September' songwriter rips Taylor Swift's Earth, Wind & Fire cover

Taylor Swift was blasted Friday over her cover of the Earth, Wind & Fire 1978 classic, “September.”

Allee Willis, who was one of the songwriters behind the 1979 hit, criticized Swift for her rendition, according to Spin Magazine.

“I didn’t really think she did a horrible job. Yes, I felt it was as lethargic as a drunk turtle dozing under a sunflower after ingesting a bottle of Valium,” Willis said in Detroit. “…And I thought it had all the build of a one-story motel, but, I mean, the girl didn’t kill anybody. She didn’t run over your foot. She just cut a very calm and somewhat boring take of one of the peppiest, happiest, most popular songs in history.”

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Swift released the cover in April, and Willis initially issued a positive statement about the song at her publicist’s request, the magazine reported Willis said she was initially “thrilled” by Swift’s release.

But now Willis changed her tune. The 70-year-old songwriter also took a shot at Swift for changing the opening line from the “21st night of September” to the 28th.

“Everyone has a right to do with a song what they please, so go on with your own bad self, Taylor Swift,” Willis said.

"Yes, I felt it was as lethargic as a drunk turtle dozing under a sunflower after ingesting a bottle of Valium."

- Allee Willis

“I’m honored you’d choose to do my song and that it meant enough to you that you wanted to personalize it to the goddamn 28th night of September, that you wanted to cover it with banjo…and that you changed the sacred ba-de-ya to the more Caucasian ah-ah-ah and make it sound more like a field of daffodils than a ‘Soul Train’ line,” she added.

Willis, who is set to be inducted into the Songwriters Hall of Fame, started colaborating with Earth, Wind & Fire in 1978 and wrote "September" over the course of a month, she told NPR in 2014.

It debuted on the Billboard charts at No. 8.

Ryan Gaydos is an editor for Fox News. Follow him on Twitter @RyanGaydos.