Calvin Tucker, Jr., a federal prisoner convicted of crack cocaine offenses, appeals the district court’s denial of his 18 U.S.C. § 3582(c)(2) motion for a sentence reduction. After review, we affirm. 1

Under § 3582(c)(2), a district court may modify an already incarcerated defendant’s term of imprisonment if the defendant’s sentence was “based on a sentencing range that has subsequently been lowered by the Sentencing Commission pursuant to 28 U.S.C. § 994(o).” 18 U.S.C. § 3582(c)(2); see also U.S.S.G. § lB1.10(a)(l). However, “[wjhere a retroactively applicable guideline amendment reduces a defendant’s base offense level, but does not alter the sentencing range upon which his or her sentence was based, § 3582(c)(2) does not authorize a reduction in sentence.” United States v. Moore, 541 F.3d 1323, 1330 (11th Cir. 2008), cert. denied, — U.S. —, 129 S.Ct. 965, 173 L.Ed.2d 156 (2009), and — U.S. —, 129 S.Ct. 1601, 173 L.Ed.2d 689 (2009); see also U.S.S.G. § 1B1.10(a)(2)(B). A reduction is not authorized if the amendment does not lower a defendant’s applicable guidelines range “because of the operation of another guideline or statutory provision.” U.S.S.G. § 1B1.10 cmt. n. 1(A).

The district court did not err in denying Tucker’s § 3582(c)(2) motion. Tucker’s § 3582(c)(2) motion was based on Amendment 706 to the Sentencing Guidelines, which reduced most of the offense levels in U.S.S.G. § 2Dl.l(c) applicable to crack cocaine offenses. See U.S.S.G.App. C, amends. 706, 713. Because Tucker was designated a career offender at his original sentencing, his offense level was based on U.S.S.G. § 4B1.1, not on U.S.S.G. § 2Dl.l(c). This Court concluded in United States v. Moore that a crack cocaine defendant, like Tucker, who was sentenced as a career offender under § 4B1.1 is not eligible for a § 3582(c)(2) sentence reduction based on Amendment 706. See 541 F.3d at 1327-29.

Tucker argues that he falls within an exception recognized in Moore because he received a downward departure pursuant to U.S.S.G. § 4A1.3(b) for overrepresented criminal history. However, Tucker’s § 4A1.3(b) downward departure was to his criminal history category, not to his offense level. Thus, the possible exception discussed in Moore would not apply. See id. at 1329-30. In light of our circuit precedent, see United States v. Smith, 289 F.3d 696, 710-711 (11th Cir. 2002), Tucker’s other arguments about § 4A1.3(b) horizontal departures in criminal history, which leave the career-offender offense level untouched, also lack merit.

The district court correctly concluded that it did not have authority to reduce Tucker’s sentence under § 3582(c)(2).

AFFIRMED.