Even former Vice President Dick Cheney has denounced Republican presidential candidate Donald Trump’s plan to ban Muslim immigration in America.

Cheney, a decisive conservative himself, said Monday on The Hugh Hewitt Show that the ban “goes against everything we stand for and believe in.”

“I think this whole notion that somehow we can just say no more Muslims, just ban a whole religion, goes against everything we stand for and believe in. I mean, religious freedom has been a very important part of our history and where we came from,” Cheney said on a Monday appearance on the radio show. “A lot of people, my ancestors got here, because they were Puritans.”

Cheney called Trump’s plan a “mistaken notion” and said to solve refugee and immigration problems, the U.S. must examine why they need to leave their countries in the first place.

“It’s a serious problem to make certain that the people coming in don’t represent ISIS. You’ve got to set up a vetting process,” Cheney said.

Listen to Cheney here. The comments on the ban start at 19:50.