McDonald’s is making small changes to ingredients and cooking processes it said would improve the quality of its hamburgers—and is bringing back the Hamburglar to market them.

The fast food chain said the improved burgers have already been rolled out in Canada, Belgium and Australia, and are now rolling out in the U.S. in a debut expected to be complete by early 2024.

The changes include softer, “pillowy” toasted buns; “perfectly” melted cheese; juicier caramelized flavor by adding white onions to the patties while they are still on the grill; and a greater quantity of special sauce on Big Macs.

“We found that small changes, like tweaking our process to get hotter, meltier cheese and adjusting our grill settings for a better sear, added up to a big difference in making our burgers more flavorful than ever,” Chad Schafer, senior director of culinary innovation of McDonald’s USA, said in a press release.

McDonald’s is promoting the changes by bringing back the Hamburglar, a character from its McDonaldland past. The ads, from Wieden+Kennedy New York, show the character casing and stealing burgers. They will be seen in markets as the improved burgers become available.

The Hamburglar was introduced in 1971 and has undergone a number of changes over the years, including reappearing as a fit dad to introduce the Sirloin Third Pound Burger in 2015. He last appeared as part of McDonald’s Cactus Plant Flea Market promotion last year.

Some diners may have already noticed the difference. One diner, who said she recently had Big Macs in Canada and in the U.S., strongly favored the Canadian burger. In the U.S., “the bun was dry, the meat was dry and the cheese was crusty,” Sierra Riley, a contributing writer to Narcity Canada, stated in a review.

McDonald’s has made periodic improvements to menu items. In 2018, it removed artificial preservatives (with the exception of the pickle), artificial flavors and coloring from its seven classic burgers. It also made changes that year to the Quarter Pounder with Cheese, transitioning to fresh beef cooked to order, and an improved bun.