At a supervised-release revocation hearing, Charles Williams admitted to the district court 1 that he had violated several of *870 his release conditions while serving a period of supervised release on a federal criminal sentence. The court revoked supervised release and imposed a revocation sentence of 21 months in prison — the bottom of the Chapter 7 revocation range— and 1 year of additional supervised release. On appeal, Williams contends that the sentence is substantively unreasonable because it is greater than necessary to comply with the purposes of 18 U.S.C. § 3558(a). After careful review, we conclude that the court did not abuse its discretion. See United States v. Miller, 557 F.3d 910, 915-16 (8th Cir. 2009) (standard of review). The judgment is affirmed, and we grant counsel leave to withdraw.