A new state law will require people to prove their citizenship when they register to vote in South Dakota state and local elections.

Republican Gov. Larry Rhoden signed the legislation Thursday. An emergency clause puts the law into effect immediately, before the June 2 primary election, rather than the usual July 1 effective date of new laws. The voter registration deadline for the primary election is May 18.

“In South Dakota, we do things right, especially when running our state elections,” Rhoden said in a news release. “This bill ensures only citizens vote in state elections, keeping our elections safe and secure.”

The legislation passed South Dakota’s Republican-dominated Legislature earlier this year by votes of 28-6 in the Senate and 64-3 in the House.