McDonald's is making its biggest ever change to the Big Mac

McDonald's is testing some big changes to its core menu item: the Big Mac.

The chain is testing a "Grand Mac" and a "Mac Jr." The "Grand Mac" has a third of a pound of more beef than the regular Big Mac and, an extra slice of cheese, and a larger bun, Columbus Business First reports.

The Mac Jr. is a single-patty burger designed to be eaten on the go.

The chain is testing the new burgers through June 6 at hundreds of restaurants in central Ohio and Dallas/Ft. Worth.

Nomura analysts Mark Kalinowski said the tests are a good sign for McDonald's.

"We view the new tests... as a sign of the company's evolving willingness to have no 'untouchables' on the menu," Kalinowski wrote in a note to clients.

He said he's hoping McDonald's also tweaks its french fries.

"We look forward to some of the french fry line extensions we've seen overseas (such as McDonald's Australia's Loaded Fries) perhaps being tested stateside one day, if we're fortunate.," he wrote.

McDonald's also recently revealed it would be building a new restaurant with all-you-can-eat fries.