GOP presidential nominee Donald Trump frequently complains about the possibility of “voter fraud” swaying the 2016 presidential election in favor of Democrats, and on Sunday he told supporters in Colorado they should take secondary steps ― ones that could result in fraudulent vote tallies ― in order to guard against this.

Colorado is one of three states in the nation where ballots are mailed to all registered voters and can be filled out and returned by mail. Voters are also welcome to vote in person.

“Who here has sent in their ballot?” Trump asked a crowd of more than 2,000 supporters at a rally in Greeley. The crowd replied with a roaring affirmative cheer.

Trump then asked, “When you send your ballot in, do you think it’s properly counted?” The crowd was quiet for a second before people realized that the correct answer was “No!”

“You can check on your ballot to make sure it’s counted properly,” Trump said. “You can go to [Greeley voting location] University Center and they’ll give you a ballot, a new ballot. They’ll void your old ballot and give you a new ballot. And you can go out and make sure it gets in,” Trump said.

“In some places, they probably do that four or five times, but we don’t do that,” he added.

Trump appeared to be unaware that Colorado law prohibits voters who have already sent in their ballots by mail from “voiding” them and getting a new ballot so they can vote in person.

According to the Secretary of State’s office, the statewide voter registration system reads a unique barcode on each ballot sent in by mail, a process known as “binking in.” Once a ballot has been read, the registration system logs a particular voter as having voted. After that happens, the system won’t accept a second ballot from that person under any circumstances, and won’t “void your old ballot” so you can vote in person, as Trump suggested.

Colorado is not the only state where Trump has sowed confusion and mistrust of voting systems. Across the country, Trump has repeatedly fanned fears among supporters that the election would be “rigged” and “stolen” from him, rhetoric that he has ratcheted up in recent weeks as he’s fallen further and further behind in the polls. An overwhelming majority of academics, pollsters and scientists have dismissed the notion of large-scale voter fraud as a myth.

So far this cycle, very few voters have been investigated on suspicion of voter fraud, and the most high-profile case to date involved an Iowa Trump supporter.

But whereas most states have long-established methods of documenting and tallying votes, Colorado will be using a new system this year, raising the possibility of confusion.

All registered Colorado voters this cycle will be sent ballots in the mail, an initiative aimed at making it easier for people to vote. Those who didn’t receive ballots, or who lost their mail-in ballots are also welcome to vote in person, according to the Colorado secretary of state’s website.

This article has been updated with additional information about how Colorado’s voting process operates.

Editor’s note: Donald Trump regularly incites political violence and is a serial liar, rampant xenophobe, racist, misogynist and birther who has repeatedly pledged to ban all Muslims — 1.6 billion members of an entire religion — from entering the U.S.