Amid negotiations over possible changes to the North American Free Trade Agreement, an immigration lawyer says it’s becoming more difficult for Canadians to cross the U.S. border for work.

In 2016, more than 1.1 million Canadians were granted temporary visas to work in the United States. That’s one-third of all applicants seeking visas to work in the U.S. Thanks to NAFTA, Canadians have the ability to apply for special work visas that aren’t available to other nationalities.

However, as U.S. President Donald Trump threatens to rip up the agreement and reform his country’s immigration system, some Canadians applying for visas are encountering stricter guidelines and longer waits.

Immigration lawyer Nan Berezowski told CTV’s Your Morning that border officers tasked with adjudicating these cases are receiving additional pressure from the government to follow new policy guidelines.

“Often this policy guidance is restrictive,” she said. “It’s narrower than it used to be.”

At the border, these changes could mean more questions, requests for documentation and increased scrutiny of forms, Berezowski said.

For Canadians, especially, the immigration lawyer said the special advantages they enjoy under NAFTA could be in jeopardy if Trump follows through on his threat to dissolve the agreement.

“For the time being, what we’re seeing is a slow erosion of those advantages,” Berezowski explained. “That erosion is due to more restrictive interpretation of the law, of the treaty, as it is now.”

Berezowski said, as a result of the changes, her workload has doubled in the last year.

“It’s the same law. It’s the same procedure, but it’s twice the work and twice the headache,” she said.

The stricter guidelines may also serve as a disincentive for Canadian companies sending employees to the U.S. for conferences, speaking engagements and other work, Berezowski warned. She also said U.S. businesses may be less inclined to hire Canadians because of the restrictions.

In order to ensure a smooth trip across the border, Berezowski advises Canadians to make sure all of their paperwork is accurate.

“It’s really important to have everything done perfectly,” she said. “I say the T’s have to be crossed three times and the I’s have got to be dotted three times.”