Get ready to pay higher airfare just in time for the busy summer travel months. Ticket prices rose by $5 for one-way domestic flights on American Airlines, according to a new report from CNN.

American Airlines isn’t the only airline raising ticket prices. Hawaiian Airlines raised prices and Southwest Airlines upped ticket prices in various markets across the country, per the same CNN report. The fare increases were unearthed by JPMorgan airline analyst Jamie Baker, who published a research note.

Fuel costs have been coming down over the past several months, adding to the surprise of recent fare hikes. Lower fuel costs strengthen the profits of airlines.

On a separate note, American Airlines and Southwest Airlines are among the U.S. carriers that fly the grounded Boeing 737 MAX jet. The jet was grounded after two deadly crashes occurred over a period of roughly six months that killed more than 300 people. United Airlines also flies the grounded 737 MAX jet. Delta Air Lines does not operate the 737 MAX.

American Airlines said back in April that it plans to take a $350 million hit from the grounded 737 MAX planes.

It remains unclear if the fare increases are in response to the costs associated with the grounded 737 MAX jets.

Still, more and more travelers are planning trips this summer. Some 71% of Americans plan to take a trip this summer, compared to 58% last year, according to a survey from Discover.

Just over one month ago, in early May, Southwest Airlines raised prices by $5 on some 180,000 fares, according to CNBC.