Sam Smith will be sharing his songwriting royalties for Stay With Me with Tom Petty and Jeff Lynne.

Shortly after the British singer's single came out last April, sharp-eared listeners noticed a similarity between Stay With Me and Petty's 1989 hit I Won't Back Down, which he wrote with Lynne.

They weren't the only ones. A representative for Smith says he and two other Stay With Me writers, James Napier and William Phillips, "came to an immediate and amicable agreement" with Petty and Lynne and now list them as co-writers of the song.

The claim was settled in October, according to British newspaper The Sun, with Petty and Lynne splitting a 25% share of songwriting royalties of Smith's song, which is nominated for song of the year at the Feb. 8 Grammy Awards.

Smith's representative says, via a statement, that the singer wasn't familiar with I Won't Back Down when he wrote Stay With Me but acknowledged a coincidental likeness when he heard the Petty/Lynne song.

Michael Harrington, a professional musicologist who specializes in federal copyright matters, also heard the similarity when a friend played him Smith's record several months ago. "It got to the chorus, and I just started smiling," Harrington says. "I said, 'Oh, yeah, that's I Won't Back Down.' That's pretty close, just the slightest differences. Especially compared to what's in court these days, this one is really solid."

According to Harrington, the two songs have a sequence of almost identical phrases in Smith's chorus and Petty's verses that made a successful claim of copyright infringement likely.

"If you took just the first phrase of the Tom Petty and Sam Smith and compared them, I would say, 'So what? I can find that in all sorts of music from Cream, Robert Johnson, Debussy,' " says Harrington, who has presented the two songs when discussing infringement in classes at Harvard Law School, Berklee College of Music and SAE Nashville, where he is a faculty chairman. "The fact that it keeps going and going: there are several phrases, and the rhythms are the same or extremely close to being the same. At some point, the similarity goes on too long."

The full statement from Smith's representative reads as follows: "Recently the publishers for the song I Won't Back Down, written by Tom Petty and Jeff Lynne, contacted the publishers for Stay With Me, written by Sam Smith, James Napier and William Phillips, about similarities heard in the melodies of the choruses of the two compositions. Not previously familiar with the 1989 Petty/Lynne song, the writers of Stay With Me listened to I Won't Back Down and acknowledged the similarity. Although the likeness was a complete coincidence, all involved came to an immediate and amicable agreement in which Tom Petty and Jeff Lynne are now credited as co-writers of Stay With Me along with Sam Smith, James Napier and William Phillips."

Here are the two songs in question. Judge their similarities for yourself.