The appellant, Michael Leon Jackson, challenges his judgment and sentence for robbery, an offense he committed on May 23, 1996. He contends he was improperly sentenced to thirty years’ imprisonment as a violent career criminal under section 775.084(1)(c), Florida Statutes (1995), an amendment to section 775.084, Florida Statutes (1993), by the passage of chapter 95-182, Laws of Florida — the Gort Act. See State v. Thompson, 750 So.2d 643 (Fla.1999). We reverse Jackson’s sentence and remand this cause for resentencing in light of the Florida Supreme Court’s recent decision in Thompson, which declares chapter 95-182 unconstitutional as violative of the single subject rule. We do not address Jackson’s challenge to the imposition of $6 in discretionary costs, as that issue was not preserved, does not constitute prejudicial error, and is thus not cognizable on appeal. See § 924.051, Florida Statutes (Supp.1996). Jackson’s robbery conviction is otherwise affirmed.

Affirmed in part, reversed in part, and remanded.