Boeing said Sunday it had reached a wage agreement with the union representing Seattle workers, ending weeks of negotiations and ending a strike threat.

The International Association of Aerospace and Machinists (IAM) had sought a 40% raise in the first full negotiations with Boeing (NYSE:) in 16 years.

An interim agreement which will become effective after ratification

valid for four years and includes a general salary augment of 25% for all employees over the duration of the contract.

The agreement also includes a commitment to build a novel Boeing plane in the Puget Sound region if ratified by 11:59 p.m. Sept. 12, the company said.

The IAM represents about 30,000 workers building Boeing’s 737 MAX planes in Washington state, where the planemaker also employs more than 66,000 people to build the wide-body 767 and 777 planes. Unionized workers voted to strike in July.

The agreement provides some relief for Boeing, which has been grappling with a production slowdown and regulatory scrutiny following an incident in January in which a door plug broke off. Alaska Air (NYSE:) passenger plane in the air.