Brazilian carrier Gol has ordered 15 additional Boeing 737 Max 8s and converted existing orders for 30 to the Max 10.
The deal grows Gol's total Max orders to 135 aircraft, says Boeing.
"This new order aligns with our strategic policy of reducing operating costs by operating a standardised fleet," states Gol chief executive Paulo Kakinoff. "We are confident that the 737 Max 10 will offer significant competitive advantages for Gol and enable us to continue to modernise with new aircraft."
The Max 10 will provide capacity for 30 more passengers than the Max 8, which seats up to 186 passengers in Gol's configuration.
Gol took delivery of its first Max last month, and is set to be the largest operator of the type in Latin America. Gol, already an all-737 operator, had previously also agreed to lease five Max 8s from GECAS, in addition to its order with Boeing.