Croatia, the newest country to join the EU, is set to hold a referendum on whether to allow same-sex marriages later this year.

More than 700,000 people signed the recent petition to change the constitution to define marriage as “the lifelong union of a woman and a man.”

Associated Press reports that Parliament on Friday voted to hold a ballot held on December 1 with the question:”Do you agree that marriage is matrimony between a man and a woman?”

If a majority vote “yes” in the referendum, the Croatian constitution will be amended to block same-sex marriages.

While currently Croatia does not allow same-sex marriages, many conservatives fear it could become possible after it was announced last year that the Social Democratic Party would be considering same-sex “domestic partnerships.”

Zeljko Reiner of the main conservative HDZ party said: “It is simply the question of safety that something… which is a basis of the Croatian society does not change.”

Gay rights activists have condemned the referendum as discriminatory, saying it infringes on basic human rights.

Activist Sanja Juras said: “This is undoubtedly a human rights issue and as such it cannot be put to a referendum.”

Under Croatian law, a referendum does not require a majority voter turnout to be valid, meaning a small number of voters would be enough to block same-sex marriages.

A Croatian gay pride parade was held in June against against the backdrop of the proposed referendum.

LGBT campaigners against the referendum marched in Croatia’s capital city, Zagreb. ”We don’t want to hear any more that we’re second class citizens or guests in our own country,” stated one supporter.