Days after workers at two Verizon stores in Washington State voted to unionize, the telecom giant fired a worker pushing to organize nearby stores.

The organizer, Jesse Mason, said the company fired him without warning, citing a minor infraction. He’s fighting to get his job back, and the union helping organize the Verizon retail workers has now filed an Unfair Labor Practice complaint with the National Labor Relations Board.

The firing could represent an escalation in Verizon’s efforts to quash a potential worker uprising in its retail stores, as corporate America stares down a growing wave of unionization efforts sweeping through major brands like Starbucks and Amazon.