which exceeded 13 months, are at issue. Hurtado also filed two letters of supplemental authority pursuant to Fed. R.App.P. 28(j). In the first letter, Hurtado cites to United States v. Booker, 543 U.S. —, 125 S.Ct. 738, 160 L.Ed.2d 621 (2005), and argues that the district court erred by applying the guidelines in a mandatory fashion. In the second letter, Hurtado cites to Shepard v. United States, — U.S. —, 125 S.Ct. 1254, 161 L.Ed.2d 205 (2005), and argues that the district court erred under Shepard in determining facts “about a prior conviction,” as opposed to a “fact of a prior conviction.” We review a defendant’s preserved constitutional challenges to his sentence de novo but will reverse and remand only for harmful error. See United States v. Paz, 405 F.3d 946 (11th Cir.2005) (<HOLDING>). We further explained in Paz as follows: A
holding that statutory construction is a question of law which this court reviews de novo recognizing that this court reviews de novo the trial courts interpretation and application of a statute to undisputed facts holding that judge found sentence enhancements mandatorily imposed under the guidelines that result in a sentence greater than that authorized by the jury verdict or facts admitted by the defendant violate the sixth amendments guarantee of the right to trial by jury recognizing that appellate court reviews questions of law de novo holding that this court reviews a booker issue de novo where the defendant objected in the district court to sentence enhancements based on facts not found by a jury nor admitted by the defendant