MEMORANDUM**
Jose Martinez challenges his sentence of twenty-four months for importation of marijuana in violation of 21 U.S.C. § 960. We have jurisdiction pursuant to 28 U.S.C. § 1291, and we affirm.
Martinez waived his right to appeal the district court’s two-point sentence enhancement under U.S. Sentencing Guideline § 3B1.4 by failing to raise it in his opening brief. ‘We ‘will not ordinarily consider matters on appeal that are not specifically and distinctly argued in appellant’s opening brief.’ ”1 We conclude that the circumstances of this case do not warrant deviating from this general rule.2
Although Martinez did not waive his right to challenge the constitutionality of 21 U.S.C. § 960,3 United States v. Mendoza-Paz 4 forecloses his argument.5
His final argument, that § 960 requires knowledge of the type and quantity of the controlled substance at issue, fails as well. When drug quantity and type expose a defendant to a higher statutory maximum sentence than he would otherwise receive, knowledge and quantity must be charged and proved.6 In circumstances such as these, however, when drug quantity and type did not expose a defendant to a higher maximum sentence, no such requirement applies.7
Therefore, we AFFIRM.
AFFIRMED.