Fatburger’s parent, Fat Brands, is to acquire the US restaurant chain Johnny Rockets.

The acquisition, worth about US$25 million, is expected to be completed this September.

Founded in 1986, Johnny Rockets is known for its 1950s diner-style decor, serving hamburgers, sandwiches, hand-spun shakes and malts. The restaurant chain operates more than 325 locations across more than 25 countries.

“Similar to Fatburger, Johnny Rockets got its start in Los Angeles, and we couldn’t be more pleased to add another true staple in our home city to our portfolio,” said Andy Wiederhorn, president and CEO at Fat Brands. “This acquisition is a transformative event for Fat Brands in terms of scale and brand awareness. We see a lot of synergy with Johnny Rockets and our current restaurant concepts and we are eager to take the brand to new heights.”

The acquisition of Johnny Rockets will increase the number of Fat Brands’ franchised and company-owned restaurants to more than 700 with annual system-wide sales exceeding US$700 million, according to the company.

Fat Brands currently owns eight restaurant chains, including Fatburger, Buffalo’s Cafe, Hurricane Grill & Wings, Elevation Burger, and Bonanza Steakhouses, and franchises more than 375 units worldwide.