Canada is open to renegotiating North American Free Trade Agreement with the U.S., the country’s ambassador to Washington said on Wednesday.

President-elect Donald Trump has called NAFTA “the worst deal in history,” but Ambassador David MacNaughton said any agreement can be improved. For starters he would like to add free trade on lumber to the table, The Associated Press reported. 

If NAFTA was scrapped, the original trade agreement between Canada and the U.S. would be put back into force, and MacNaughton said he doubts the U.S. would want to end that. 

Canadian Prime Minister Justin Trudeau spoke to Trump Wednesday night and invited Trump to visit Canada at the earliest opportunity. Trump invited Trudeau to the White House, as well.

The Liberal prime minister’s openness to refugees, trade, and the environment stands in sharp contrast to Trump’s campaign stances, but Trudeau said he will work closely with the president-elect. 

“The prime minister and the president-elect reiterated the importance of the Canada-United States bilateral relationship, and discussed various areas of mutual interest,” Trudeau’s office said.

Trump has expressed interest in TransCanada’s Keystone XL pipeline running from Alberta to the U.S. Gulf Coast that President Barack Obama opposed. Trump has said he wants the U.S. to get a share of the profits if the pipeline were to be built.