Two musicians have sued rapper Kendrick Lamar for copyright infringement, accusing him of using their music in his own song without their permission.

Composer and musician Eric S. Reed claims Lamar blatantly copied the music from his work "The Thorn" -- which he wrote for his co-plaintiff, drummer Willie Jones III -- and used it as a sample in the rapper's 2011 single "Rigamortis."

"The Thorn," according to Reed, was composed in 2009 and came out in Jones' 2010 recording "The Next Phase (WJ3)."

The musicians accused Lamar of having usurped their music, a horns-driven jazz piece, and simply adding his own lyrics to it. They claim they did not give the rapper permission to use "The Thorn" in any way, including the many versions and songs which Reed and Jones say feature their original recordings.

"'The Thorn' is not merely a part of 'Rigamortis' or even the heart of 'Rigamortis"; it is 'Rigamortis,'" Reed and Jones' lawsuit says. "The distinctive and catchy refrain from 'The Thorn' sound recording, sped up a bit, repeats as a continuous loop throughout the entire 'Rigamortis' song while Lamar raps over it," according to the lawsuit.

Reed and Jones also allege that a YouTube video of William T. Brown, a co-defendant in the case, features him creating the Lamar song and, in a portion of it, shows his computer monitor where the words "Willie Jones III The Thorn" are visible.

"Defendants did not play any instruments or contribute any original musical performance to the 'Rigamortis' sound recording," the lawsuit mentions. "The clever melodic triplets, infectious rhythm, and commanding horns from 'The Thorn' are copied to 'Rigamortis' directly from Jones' sound recording," it said.

Reed and Jones allege that the rapper never gave them royalties or even a credit for the music, TMZ reports. They are seeking $1 milion in damages, along with "Rigamortis'" profits from the alleged infringement.

The musicians are also demanding payment of all their attorney's fees and costs.