Barnes & Noble isn’t happy about the proposed settlement the U.S. government has offered to Apple and some book publishers. The government sued the companies in April over colluding to fix prices on e-books, and Barnes & Noble says the proposed settlement in that suit would not only harm book sellers, but also “millions and millions” of customers.

Under the settlement, three of the five publishers named in the suit—Simon & Schuster,  Hachette Book Group and HarperCollins—agreed to end their contracts with Amazon, Google and any other e-book seller that lets publishers set their own prices (a pricing practice known as the “agency model”). Apple and the other two publishers—Penguin and Macmillan—plan to fight the suit.

On Thursday, Barnes & Noble sent a letter to the U.S. Department of Justice (DOJ) saying that the settlement would lead to “higher overall average e-book and hardback prices and less choice, both in how to obtain books and in what books are available.” The book seller also said that Amazon’s adoption of the agency model had lowered its e-book market share from 90 percent to 60 percent.

“We think the Justice Department has made a gross error and gotten this wrong,” Gene De Felice, Barnes & Noble’s general counsel, told the LA Times. “Their attack on publishers, small business and free commercial relationships is really unprecedented.” He went on to say that the DOJ appears to be “supporting a monopoly by Amazon.”