A Niagara Falls man who was convicted of unlawful possession of a firearm was sentenced Monday to 21 months in prison by U.S. District Judge Richard J. Arcara.

Prosecutors said Melvin L. Calhoun, 23, was found with a loaded .38-caliber pistol under his mattress and quantities of marijuana when a search warrant was executed at his home on 12th Street in October 2010. They said he admitted to being a marijuana user and having the pistol in connection with distributing the drug.