Mich. Comp. Laws § 700.2506: Choice of law as to execution.

Sec. 2506.

A written will is valid if executed in compliance with section 2502 or 2503, with the law at the time of execution of the place where the will is executed, or with the law of the place where, at the time of execution or at the time of death, the testator is domiciled, has a place of abode, or is a national.