LANSING, Mich. (AP) — Certain retired school employees could return to work without putting at risk their pension under legislation headed to Gov. Rick Snyder for his expected signature.

The bill approved Tuesday is designed to address a shortage of substitute teachers and full-time teachers in some subjects.

A law allowing educators who retired after mid-2010 to teach again without losing their pension expired last year. The legislation re-enacts provisions until 2018.

Schools administrators and companies they contract with for substitutes say the law’s expiration has limited their pool of qualified substitutes.

Under the bill, retirees hired in shortage subjects could work three years without affecting their retirement benefits. Retirees working as substitutes could receive full benefits as long as they make no more than one-third of their final average compensation in a year.