The credit card company is raising rates on more than 1 million cards, Bloomberg reports. Annual rates for some customers will climb by an average of 2.5 percentage points, for a total of at 12.99% at the lowest.

Bloomberg notes that American Express sent letters to the customers affected explaining that the changes were made because the company discovered that rates for its cards were below that of its competitors.

This is American Express’ first rate bump in more than five years.