Boeing Co. is making an extensive change to the flight-control system in the 737 MAX aircraft involved in October’s Lion Air crash in Indonesia, going beyond what many industry officials familiar with the discussions had anticipated.

The change was in the works before a second plane of the same model crashed in Africa last weekend—and comes as world-wide unease about the 737 MAX’s safety grows.

The change would mark a major shift from how Boeing originally designed a stall-prevention feature in the aircraft, which were first delivered to airlines in 2017.

U.S. aviation regulators are expected to mandate the change by the end of April.

Boeing publicly released details about the planned 737 MAX software update on its website late Monday.