An Indiana man is suing Britney Spears for copyright infringement, alleging he is the one who wrote "Sometimes," which she recorded.

Steve Wallace's court documents, filed last week in Indianapolis federal court, acknowledge he did not formerly copyright the song until 2003. But weeks after writing the song in 1990, he says he got a "poor man's copyright," that is, sealing the song in an envelope and mailing it to himself for the postmark.

But court records show Spears obtained the copyright for the song in January 1999, E! Online reported Friday.

Wallace is seeking $150,000 for each instance of copyright infringement. It was not clear if he would be seeking additional damages.