Steven Joseph Guidry was convicted following a guilty plea to one count of possessing stolen firearms, in violation of 18 U.S.C. § 922(j). He argues that the district court erred by imposing a sentence under a mandatory federal sentencing guideline scheme, which was held to be unconstitutional in United States v. Booker, 543 U.S. 220, 125 S.Ct. 738, 160 L.Ed.2d 621 (2005). The Government concedes that the issue was preserved in the district court, that the district court committed error, and that it cannot prove that *686 the error was harmless. In light of the foregoing, we VACATE the district court’s sentence and REMAND for resentencing in accordance with Booker.