Mich. Comp. Laws § 750.520f: Second or subsequent offense; penalty.

Sec. 520f.

If a person is convicted of a second or subsequent offense under section 520b, 520c, or 520d, the sentence imposed under those sections for the second or subsequent offense shall provide for a mandatory minimum sentence of at least 5 years.

For purposes of this section, an offense is considered a second or subsequent offense if, prior to conviction of the second or subsequent offense, the actor has at any time been convicted under section 520b, 520c, or 520d or under any similar statute of the United States or any state for a criminal sexual offense including rape, carnal knowledge, indecent liberties, gross indecency, or an attempt to commit such an offense.