Mich. Comp. Laws § 117.38

Sec. 38. It is intended by this act to re-enact sections 21, 22, 23 and 24, as above amended pursuant to the adoption of the amendment to section 21 of article 8 of the state constitution by vote of the electors on November 5, 1912, so that cities under existing charters heretofore granted by the legislature shall have the same right and power to amend such charters under the act hereby amended as cities that have adopted complete charter revisions.