FYROM PM Zoran Zaev labeled Greece’s demand that his country amends its constitution “unreasonable”. In an interview to the “Financial Times”, Mr Zaev said that despite the differences between the two countries on the name he was optimistic a mutually accepted solution could be reached.
Mr Zaev said his country had no claims on Greece, making it clear in the interview that Greece’s demands on the issue of the Constitution risked torpedoing the deal that each side said it wanted.

“Now the new requirement from Greece is that we need to change our constitution. But a constitution is a home rulebook. It doesn’t have implications outside the country. In any case, changing the constitution wouldn’t be a final guarantee, because a new government in the future could just change the constitution back again.”, Zaev told the Financial Times.
The Financial Times piece says the dispute between the two nations is a quarrel many outside the Balkans find baffling but adds that issue is a concern for NATO and the EU, as it has the potential of escalating into a conflict in a region that has been engulfed in violent clashes over territory and identity.

From Financial Times:

Zoran Zaev, Macedonia’s prime minister, has said his country and Greece are moving closer to solving one of Europe’s most intractable diplomatic disputes — the quarrel over what name the former Yugoslav republic should use. The two countries have been at odds since the early 1990s over whether Greece’s neighbour has the right to call itself Macedonia, a name that politicians in Athens say implies a territorial claim on an identically named region of northern Greece. Officially, the young state is known as FYROM (Former Yugoslav Republic of Macedonia). In an interview with the Financial Times in London, Mr Zaev said he was hopeful of a settlement. But he said a Greek demand for Macedonia to amend its constitution, to make clear it has no claims on Greek territory, was unreasonable and risked torpedoing the deal that each side says it wants. Mr Zaev hopes he and Alexis Tsipras, the leftist Greek prime minister, will find a compromise before a Nato summit in Brussels on July 11-12. “I’m optimistic. It’s very difficult, we’re aware of that. But it would be smart for both sides to find a solution as early as possible,” Mr Zaev said. “Now the new requirement from Greece is that we need to change our constitution.

read more at FT.com