Calbee Inc., a Japanese potato chip manufacturer, will jack up prices of snacks and cereals in Japan by 5% to 20% beginning in September due to rising material costs. Following the announcement, its shares rose as much as 5.1% in Tokyo, the largest intraday gain in more than a month.

Due to a poor potato crop and higher material costs, the company has already raised prices several times this year. To the chagrin of chip fans, it was also forced to reduce bag sizes.

“Smaller rival Koike-ya Inc. also announced price increases this month, including for their popular spicy and sour product line that will take effect in September,” Bloomberg wrote.

The snack maker’s popularity extends beyond the supermarket aisle, according to PepsiCo Inc., its largest shareholder. Its regional souvenirs of limited-edition snacks ranging from octopus-ball flavored potato sticks in Osaka to taco-rice flavored ones in a nod to a popular dish in Okinawa’s southernmost prefecture are also hugely popular, according to the company, and will cost more come fall.