Cuba's National Assembly on Saturday approved an update of the country's constitution, the final step before a national referendum expected to approve the new charter in February.

The new constitution contains more continuity than change, although it recognizes the de-facto modernization of Cuban society over the last decade. The constitution maintains Cuba as a centrally planned economy ruled by a single Communist Party, but recognizes private property for the first time and paves the way for a separate referendum on legalizing gay marriage.

It also creates the role of prime minister alongside the current president, as well as provincial governors.

Legalizing private property is a formal recognition of significant change in Cuban society since former President Raul Castro permitted home and auto sales, creating a booming real-estate market, and allowed more than half a million Cubans have permits to work as entrepreneurs. Hundreds of thousands more work full or part-time in the private sector without licenses.

The new constitution also recognizes worker-owned cooperatives for the first time as a legal form of production in every sector of the economy, while maintaining Cuba's largely inefficient and stagnant state-run industries as the central means of production.

Closing the National Assembly, President Miguel Diaz-Canel said the island's economic challenges — including a weak 1.2 percent 2018 growth rate, and similar growth expected next year — required the acceptance of private business, joint public-private ventures and coops working together. He promised to fight widespread public-sector embezzlement and corruption that makes it virtually impossible to get anything done in Cuba without a series of small bribes.

"We've called a battle, and we'll wage it, an ethical battle against corruption, illegality ... and social indiscipline," he said.

The president also promised a more responsive government, part of an initiative that has seen almost all Cuba's head of ministries start social-media accounts for the first time, some of which take questions from citizens.

"There are a lot of questions to pay attention and respond to," Diaz-Canel said. "We'll give responses to all of them as soon as it's possible, and those that we don't' have an answer to for the moment, we'll never stop searching."

He did not mention Cuba's unique two-currency system, which creates inefficiencies and distortions that are seen as one of the island's most serious economic problems. Castro called monetary unification an urgent priority before stepping down in April, but the issue has barely been mentioned since Diaz-Canel took over.

The degree to which the new constitution will actually spur change is expected to be seen only after the National Assembly approves a raft of changes to the civil and penal codes and electoral laws next year.

Language seen as the immediate precursor to the legalization of gay marriage was eliminated after widespread public objection and protests by evangelical churches. Cuban officials say the question of gay marriage will be put to a nationwide referendum, something most gay activists oppose.

The constitution was drafted by a committee led by Castro, who is still Communist Party head. It was then subjected to months of public comment in workplaces and neighborhoods across the island. Some suggested changes were approved, others rejected.

As in virtually every vote in recent memory, the National Assembly unanimously approved the draft constitution.