The American Postal Workers Union (APWU) has filed charges to the National Labor Relations Board against the Postal Service for failing to consult with the group following its recent data breach.

In a letter to members, APWU President Mark Dimondstein stated that the union was alerted of the breach at the time the rest of the public was on Monday. Postmaster General Patrick Donahoe alerted Dimondstein on Sunday night, which he described as “just a ‘courtesy call’.” He believes the union should have been notified earlier in order to bargain over the impact the breach would have on those affected.

“While the Postal Service has been aware of the security problems for months, they kept you and your union leadership in the dark,” Dimondstein said.

More than 800,000 USPS employees may have been impacted by the breach.