The merger between Quebec's two small sovereignist parties is now official: Option Nationale members approved a motion Sunday afternoon to join forces with Québec Solidaire.

The motion was backed by 90.7 per cent of the 200 ON members who voted at a party congress in Sainte-Foy, near Quebec City. Québec Solidaire OK'd the parties' amalgamation in a vote earlier this month.

Some of the ON members opposing the merger left the room in protest of the vote.

Québec Solidaire received 7.6 per cent of the vote in the 2014 provincial election and has three seats in the National Assembly. Optional Nationale, founded in 2011, only collected 0.7 per cent of the vote in that election.

Québec Solidaire's Gabriel Nadeau-Dubois reacted to ON's vote on Twitter, saying "it's a big day for the people who want to change Quebec."

. <a href="https://twitter.com/QuebecSolidaire?ref_src=twsrc%5Etfw">@QuebecSolidaire</a> et <a href="https://twitter.com/OptionNationale?ref_src=twsrc%5Etfw">@OptionNationale</a> unissent officiellement leurs forces! C’est un grand jour pour les gens qui veulent changer le Québec! <a href="https://twitter.com/hashtag/polqc?src=hash&ref_src=twsrc%5Etfw">#polqc</a> —@GNadeauDubois

"It's a big step forward for independence," Nadeau-Dubois said when the merger plans were announced in October.