There is plenty to consider when a country decides to change its name. What impact, for example, will it have on its government institutions, its passports, or its currency? Will the change affect its national airline or its sports teams? How does a country go about registering its new name with international institutions?

When Macedonians head to the polls later this month to cast their vote in a national referendum on whether to change their country’s name from the Republic of Macedonia (or the Former Yugoslav Republic of Macedonia, as its known by international bodies) to the “Republic of North Macedonia,” it’s unlikely they will be thinking about any of those questions. Instead, the vote will center on what will be gained by Macedonia if it does concede to this renaming and, perhaps most importantly, what it will lose out on if it doesn’t.

The referendum, which is scheduled to take place on September 30, will ask Macedonian voters to answer “yes” or “no” to the following question: “Do you support EU and NATO membership by accepting the agreement between Macedonia and Greece?” That the proposed new name doesn’t even feature in the question is telling because, in truth, this referendum isn’t just about a name. It’s about a deal that was made by the Greek and Macedonian governments in which both sides agreed they were ready to end their decades-long name dispute over who gets to claim the name “Macedonia.” (Greece has opposed the former Yugoslav republic being called “Macedonia” since its inception in 1991, arguing that it implies territorial aspirations over a northern Greek province of the same name.) In July, Macedonian Prime Minister Zoran Zaev and Alexis Tsipras, his Greek counterpart, struck a deal: If Macedonians agreed to add “North” to their country’s official name, the Greeks would drop their opposition to Macedonian membership in the European Union and NATO, which Athens has consistently vetoed.

So what’s so difficult about adding a five-letter adjective? A lot, as it turns out. Should Macedonians vote in favor of the name change, as polls project they will, it will require more than simply updating their name plates at the United Nations. The renaming will need to be reflected across Macedonian society, from the name of its government agencies to its passports, drivers’ licenses, and its official currency. Though the deal stipulates the country’s language will still be called Macedonian and its people Macedonians, it’s unclear if the same can be said for more quotidian issues, such as the country’s domain name or even its national sports teams. The Ministry of Foreign Affairs in Macedonia, when tried for comment on those specifics, was unresponsive.

Still, Macedonians are widely expected to approve the name change, according to a recent nationwide survey, which found that 49 percent intend to vote in favor of the referendum, compared with the 22 percent who intend to oppose it. Though 16 percent said they won’t vote at all, their decision could still impact the outcome: Under Macedonian law, slightly more than 50 percent of the country’s 1.8 million registered voters need to take part in order for the referendum to be considered valid. Though the referendum is not binding and the country’s parliament could still put the name change to a vote regardless of the outcome, opponents of the move could use low turnout to undermine the effort. Some of the deal’s opponents have already called for their supporters toboycott the vote.

And that’s not the only challenge. Even if the referendum passes with more than 50 percent voter turnout, Macedonian lawmakers would still need to approve a constitutional amendment to reflect the change—a process that “is actually quite complex,” James Ker-Lindsay, a visiting professor at the London School of Economics, told me. He noted that though the name change has the support of Zaev, the Macedonian prime minister, and his ruling Social Democratic Union party, it is opposed by the nationalist opposition party, the VMRO-DPMNE. With control of just 60 seats in parliament, Zaev’s party will need the backing of at least 20 others to get the two-thirds majority needed for the amendment to pass. “So they can still block this,” Ker-Lindsay said of the VMRO-DPMNE. “The big question is: Will it be the case that if it goes through in the referendum, that they’ll basically give up on their opposition and say, ‘The people have spoken, we’ll accept it,’ or not?”

If the deal does pass through the Macedonian Parliament, it must then be ratified by lawmakers in Athens. There, too, the name change faces opposition. Though Tsipras, the Greek prime minister, has enough seats in parliament to approve the deal with a simple majority, he may not for long. His party’s coalition partner, the right-wing Independent Greeks, threatened to quit the government this week over the name issue, which could potentially trigger fresh elections.

But perhaps the greatest threat to the deal isn’t just politics in Skopje or Athens—it’s Russian interference. Moscow has been a vocal opponent of the deal, which it sees as a continuation of NATO expansion that undermines its influence in the Balkans. This opposition has stoked fears that Moscow could try to meddle in the outcome of the referendum—if it hasn’t already. As The New York Times reports, hundreds of new websites urging voters to boycott the referendum have appeared online in the weeks leading up to the vote, with many of them originating outside the country— a pattern that fits with instances of Russian interference in other elections. There have already been concerns of attempted meddling in Greece, which in July expelled two Russian diplomats suspected of trying to undermine the name-change negotiations. “There is real worry that the Russians might try and undermine this process in whatever way they can,” Ker-Lindsay said. “If they did it in Greece, you can be almost certain that they are looking to try and do it in Macedonia.”

In a visit to the region this week, American Defense Secretary James Mattis said there is “no doubt” Russia has been trying to affect the referendum, and urged Macedonians to vote. “We recognize the complex political choice ahead for your people and we support you, our Macedonian friends, exercising your own sovereign voice and your democratic responsibility to vote,” Mattis said Monday in Skopje, adding that if Macedonians approved the name change, “you would join an alliance in which countries large and small work together to uphold shared principles of national sovereignty, territorial integrity, and freedom from coercion.”

In the face of opposition from within and outside Athens and Skopje, Ker-Lindsay said the road will be difficult for both parties, who likely have only one shot to get this right. “It really would be disastrous on all sorts of levels if this didn’t pass now, because it’s taken so long to get to this stage,” he said, adding: “It’s still a very dicey process. It’s great that they signed the [July] agreement, but it’s still not there. And until it is, it isn’t. Nothing is certain at all.”