Wisconsin's strict photo ID requirements for voters will now be enshrined into the state constitution after voters approved the proposal on Tuesday's ballot.

Wisconsin is one of nine states where people must present photo ID to vote, and its requirement is the nation’s strictest, according to the National Conference of State Legislatures. Thirty-six states have laws requiring or requesting that voters show some sort of identification, according to the NCSL.

The state has required voters to use photograph identification for nearly a decade, but an amendment to the Wisconsin Constitution was seen as making it more difficult to roll back that rule.