The Wikimedia Foundation waited until immediately after its largest annual conference to say it wouldn’t voluntarily recognize its workers’ union.

Last week, Wiki Workers United, which is organized through the Communication Workers Union and represents U.S. workers at the nonprofit Wikimedia Foundation, requested voluntary recognition of their union. Wiki Workers United said that it had secured a “supermajority of union-eligible workers who have signed union authorization cards.” A group of more than 1,100 Wikipedia editors have also signed a letter of support for the union.

On Monday, just days after the massive Wikimania Conference concluded in Paris, the Wikimedia Foundation announced it would not voluntarily recognize the union and said the union would have to conduct a vote as overseen by the National Labor Relations Board.