Isaac Caldwell appeals his 57-month guilty-plea sentence for possession of a firearm by a convicted felon, 18 U.S.C. §§ 922(g)(1) and 924(a)(2). He argues that his sentence must be vacated and his case remanded for resentencing because the district court committed reversible error by sentencing him pursuant to a mandatory sentencing guidelines regime. *387 Caldwell’s objection pursuant to Blakely v. Washington, 542 U.S. 296, 124 S.Ct. 2531, 159 L.Ed.2d 403 (2004), was sufficient to preserve this issue for appeal. See United States v. Rodriguez-Mesa, 443 F.3d 397, 404 (5th Cir. 2006).

The sentence pursuant to a mandatory guidelines scheme constitutes Fanfan error. See United States v. Booker, 543 U.S. 220, 125 S.Ct. 738, 160 L.Ed.2d 621 (2005); United States v. Walters, 418 F.3d 461, 463-64 (5th Cir. 2005). The government thus bears the burden of proving beyond a reasonable doubt that the district court would have imposed the same sentence had the guidelines been advisory only. See Walters, 418 F.3d at 464. If the government cannot show that the error was harmless, we ordinarily will vacate and remand for resentencing. Id. at 463.

The government cannot meet its burden. See id. at 464-66. Because the Fanfan error requires remand for resentencing, we need not address Caldwell’s remaining challenge to his sentence. See United States v. Akpan, 407 F.3d 360, 377 n. 62 (5th Cir. 2005). Accordingly, we vacate Caldwell’s sentence and remand for resentencing.

CONVICTION AFFIRMED; SENTENCE VACATED; CASE REMANDED.