ORDER

Moushen Lassila led several conspirators who manufactured fraudulent credit cards and stole $1.5 million in merchandise. He pleaded guilty to conspiracy to commit wire fraud, 18 U.S.C. §§ 1349, 1343, and was sentenced within the guidelines range to 125 months’ imprisonment. As part of a written plea agreement, Lassila waived the right to appeal his sentence except on a few limited grounds that are not relevant here. Despite this waiver, Lassila directed his appointed counsel to appeal his sentence, but counsel now seeks to withdraw under Anders v. California, 386 U.S. 738, 87 S.Ct. 1396, 18 L.Ed.2d 493 (1967), because he cannot discern a non-frivolous basis for appeal. Lassila has re *176 sponded that he wants to challenge his sentence, see Cir. R. 51(b), but he does not add to the potential arguments evaluated by counsel. Our review is thus limited to the potential issues identified in counsel’s facially adequate brief. See United States v. Schuh, 289 F.3d 968, 973-74 (7th Cir. 2002).

Counsel identifies two possible grounds on which Lassila could challenge his sentence, but the appeal waiver makes both frivolous. An appeal waiver is enforceable so long as it is knowing and voluntary. See United States v. Lockwood, 416 F.3d 604, 608 (7th Cir. 2005). Lassila cannot contest the voluntariness of his waiver unless he challenges his guilty plea, see United States v. Whitlow, 287 F.3d 638, 640 (7th Cir. 2002), which he has not indicated that he wishes to do.

Accordingly, counsel’s motion to withdraw is GRANTED and Lassila’s motion for appointed counsel is DENIED. The appeal is DISMISSED.