The Federal Public Defender appointed to represent Johnny Noe Aparicioabarca has moved for leave to withdraw and has filed a brief in accordance with Anders v. California, 386 U.S. 738, 87 S.Ct. 1396, 18 L.Ed.2d 493 (1967), and United States v. Flores, 632 F.3d 229 (5th Cir. 2011). Apar-icioabarca has filed a response. We have reviewed counsel’s brief and the relevant portions of the record reflected therein, as well as Aparicioabarca’s response. We concur with counsel’s assessment that the appeal presents no nonfrivolous issue for appellate review. If Aparicioabarca wishes to challenge the Attorney General’s decision regarding the calculation of his sentence, he must first exhaust his administrative remedies through the Bureau of Prisons and then may file a habeas corpus petition pursuant to 28 U.S.C. § 2241. See United States v. Gabor, 905 F.2d 76, 78 (5th Cir. 1990). Counsel’s motion for leave to withdraw is GRANTED, counsel is excused from further responsibilities herein, and the APPEAL IS DISMISSED. See 5th Cir. R. 42.2.