U.S. President Barack Obama had a tough time pronouncing the name of one of Canada's biggest cities Thursday night when he spoke at the state dinner for Prime Minister Justin Trudeau.

"This is always tough," Obama started off, presumably seeing s after s after s and fearing the worst.

"Missis-swa-ah-ga? Missisag-wa?"

Dinner attendees, many laughing, tried to help the president, to no avail.

"And then we went to Toronto and Niagara Falls," Obama went on, continuing with the story he was telling. "Missisawg-wa, I can do that," he said, still mispronouncing the name.

The city's official Twitter account took the moment with good humour.