Socialist MPs of Prime Minister Socrates' party supported the reform
Portugal's parliament has voted to introduce contentious changes to the Portuguese language in order to spell hundreds of words the Brazilian way.
The agreement standardises numerous spellings and adds three letters - k, w and y - to the alphabet.
A large majority of lawmakers backed government proposals to phase in the changes during the next six years.
But a petition against the move was signed by 33,000 people who argue it is a capitulation to Brazilian influence.
Proponents counter the move will make the language more uniform globally, making such things as internet searches and legal documents easier to understand.
The agreement will standardise spelling by removing silent consonants in order for words to be spelt more phonetically, turning, for example "optimo" (great) into "otimo".
Friday's vote came after a unified form of the Portuguese language was originally agreed with seven Portuguese-speaking countries in 1991.
The official language of more than 230m people worldwide, Portuguese is spoken in Brazil, Angola, Mozambique, East Timor, Cape Verde, Guinea-Bissau, and Sao Tome and Principe, as well as Portugal.
Portugal's President Anibal Cavaco Silva is now expected to ratify the accord.