Nahum Berrios appeals from his re-sentencing by Judge Dearie. On March 6, 1991, Berrios originally pleaded guilty to a charge of conspiracy to possess cocaine with intent to distribute, in violation of 21 U.S.C. § 846. In April, he was sentenced to 210 months in prison. Thereafter, the United States Sentencing Guidelines (“Sentencing Guidelines”) were amended in a way that permitted Berrios to seek a reduction of his sentence pursuant to Sentencing Guidelines § 1B1.10. 1 The government did not oppose the motion, and Judge Dearie resentenced Berrios to 168 months in prison. On appeal, 2 Berrios raises an issue that he did not present to the district court. He claims that an *432 amendment to Sentencing Guidelines § 1B1.10(b), promulgated after his original sentencing, violates the Ex Post Facto Clause of the Constitution, art. I, § 9, cl. 3, because it prevented the court from further reducing his sentence based on certain other amendments to the Sentencing Guidelines. Because Berrios’ attorney did not raise this argument at the resentencing, Berrios asserts that he was provided ineffective assistance of counsel. We disagree.

At the time of Berrios’ original sentencing, Sentencing Guidelines § lB1.10(a) authorized a reduction in sentence pursuant to 18 U.S.C. § 3582(c)(2) 3 when the Sentencing Guidelines range is lowered subsequent to the original sentencing. However, such a reduction was authorized only in the case of Sentencing Guidelines amendments designated in § 1B1.10(c). 4 After Berrios was originally sentenced, § 2D1.1 of the Sentencing Guidelines was amended to lower the base-offense level for violations of 21 U.S.C. § 846; this amendment was designated in § 1B1.10(c) as a possible basis for a reduction in sentence under § lB1.10(a). These changes were the basis for Berrios’ successful motion to reduce his sentence.

The issue in this appeal arises from an amendment to § lB1.10(b). At the time of Berrios’ original sentencing, § lB1.10(b) provided that, in resentencing proceedings under § 1B1.10(a), the court, in determining whether and to what extent a reduction in sentence is warranted, “should consider the sentence that it would have originally imposed had the guidelines, as amended, been in effect at that time.” U.S.S.G. § lB1.10(b) (1992) (emphasis in original). Application Note 1 explained that the Sentencing Guidelines range on resentencing was “to be determined by applying all amendments to the guidelines (i.e., as if the defendant was being sentenced under the guidelines currently in effect).” Id. (emphasis added).

Amendment 504 to the Sentencing Guidelines, effective November 1,1994, altered the pertinent language in § 1B1.10(b) to provide that in determining whether and to what extent a reduction in sentence is warranted, “the court should consider the sentence that it would have imposed had the amendments) to the guidelines listed in subsection (c) been in effect at the time the defendant was [originally] sentenced.” U.S.S.G. § 1B1.10(b) (1995) (emphasis added). Application Note 2 explains that, in determining the amended Sentencing Guidelines range, “the court shall substitute only the amendments listed in subsection (c) for the corresponding guideline provisions that were applied when the defendant was sentenced. All other guideline application decisions remain unaffected.” Id. Thus, the difference between the old scheme and the new one is that, under the old scheme, a defendant would be resenteneed under the then-effective version of the Sentencing Guidelines, while, under the new scheme, a defendant would be resentenced under the version of the Sentencing Guidelines applicable to the original sentence unless a pertinent amendment was expressly designated in § 1B1.10(c).

Berrios’ ex post facto argument is that, because § 1B1.10(b) was amended between the time he was originally sentenced and the time he was resentenced, and because, also during that period, several other amendments to the Sentencing Guidelines were promulgated that would have benefited him under the prior, but not the later, version of *433 § 1B1.10(b), the amendment to § 1B1.10(b) is both “retrospective” and “disadvantageous.” See Miller v. Florida, 482 U.S. 423, 430, 107 S.Ct. 2446, 2451, 96 L.Ed.2d 351 (1987) (to violate Ex Post Facto Clause, statute must be “retrospective” and “must disadvantage the offender affected by it”); see also California Dep’t of Corrections v. Morales, 514 U.S. 499, 506 n. 3, 115 S.Ct. 1597, 1602 n. 3, 131 L.Ed.2d 588 (1995) (“the focus of the ex post facto inquiry is not on whether a legislative change produces some ambiguous sort of ‘disadvantage,’ ... but on whether any such change alters the definition of criminal conduct or increases the penalty by which a crime is punishable.”).

We believe that the amendment to § 1B1.10(b) does not violate the Ex Post Facto Clause. Under the Sentencing Guidelines, ex post facto problems usually arise when the Sentencing Guidelines are amended after a defendant commits- an offense but before he or she is sentenced. In that context, the sentencing court must apply the version of the Sentencing Guidelines in effect at the time of sentencing unless that version “results in a more severe sentence than that which would have resulted had the Guidelines version in effect at the time of commission of the crime been applied.” United States v. Rodriguez, 989 F.2d 583, 587 (2d Cir.1993). The relevant inquiry for ex post facto analysis is not whether a particular amendment to the Sentencing Guidelines is detrimental to a defendant, but whether application of the later version of the Sentencing Guidelines, considered as a whole, results in a more onerous penalty. United States v. Keller, 58 F.3d 884, 890-93 (2d Cir.1995) (noting that “had the changes detrimental to the defendants not more than offset the changes favorable to them, the later version of the guidelines would have been applicable, notwithstanding that one component of the later version would have been less favorable to defendants”).

Analogous principles apply to a situation where, as here, an already-sentenced defendant seeks to take advantage of later amendments to the Sentencing Guidelines. Section 1B1.10(b) is triggered only after a defendant seeks a reduction in sentence pursuant to § 1B1.10(a). The amendment to § 1B1.10(b) “disadvantages” only those prisoners who seek a benefit under § 1B1.10 and who therefore cannot face a harsher punishment. For example, Berrios was initially sentenced to 210 months in prison. On resentencing, he was sentenced to 168 months. Even assuming, arguendo, that the amendment to § 1B1.10(b) “disadvantaged” Berrios by limiting the district court’s consideration to only one of the intervening amendments, the amendment he invoked resulted in a net effect favoring him. Accordingly, the Ex Post Facto Clause was not violated. See Keller, 58 F.3d at 891 (holding that “when positive and negative implications of an amendment result in a net effect favoring defendants, no ex post facto problem is present,” regardless of whether ameliorative effects and detrimental effects are found in amendments to the same Sentencing Guidelines section or different Sentencing Guidelines sections).

Because we conclude that the amendment to § 1B1.10(b) does not violate the Ex Post Facto Clause, Berrios was not deprived of effective assistance of counsel at sentencing.

We therefore affirm.