OPINION
PER CURIAM.
Adolfo Lemus-Mora challenges his sentence following his conviction for reentry of a deported alien, in violation of 8 U.S.C. § 1326 (1994). Lemus-Mora’s counsel has filed a brief in accordance with Anders v. California, 386 U.S. 738, 87 S.Ct. 1396, 18 L.Ed.2d 493 (1967), challenging the district court’s failure to depart downward on the basis of Lemus-Mora’s cultural assimilation in the United States, but stating that in his opinion there are no meritorious issues for appeal. Lemus-Mora was informed of his right to file a pro se supplemental brief but did not do so.
When a district court exercises its discretion at sentencing and refuses to depart downward, its decision is not subject to review on appeal. United States v. Bayerle, 898 F.2d 28, 31 (4th Cir.1990). However, a refusal is reviewable if the court refuses to depart based on a perception that it lacks legal authority to depart. United States v. Hall, 977 F.2d 861, 863 (4th Cir.1992). Because the district court clearly knew that it had the authority to depart, the refusal is not reviewable. Hall, 977 F.2d at 863; Bayerle, 898 F.2d at 31.
We have reviewed the entire record in accordance with the requirements of Anders and find no error below. We therefore dismiss the appeal. This court requires that counsel inform his client, in writing, of his right to petition the Supreme Court of the United States for further review. If the client requests that a petition be filed, but counsel believes that such a petition would be frivolous, then counsel may move in this court for leave to withdraw from representation. Counsel’s motion must state that a copy thereof was served on the client. We dispense with oral argument because the facts and legal contentions are adequately presented in the materials before the court and argument would not aid the decisional process.
DISMISSED.