Boeing has identified two new software problems with the grounded 737 Max that must be fixed before the jetliner fly again.

According to Boeing, the issues are related to the flight-control computer and don’t affect the plane’s estimated return to service in mid-2020. The Max’s software has been redesigned after being linked to two fatal crashes that prompted a worldwide flying ban more than a year ago.

The first problem involves “hypothetical faults” in the computer’s microprocessor, which could lead the plane to climb or dive on its own, Boeing said. A safety system on the Max caused the jet to dive automatically in both accidents, but the problems aren’t related, Boeing said.

The other newly revealed fault could potentially cause the autopilot to disengage as the aircraft prepares to land. The software changes made by Boeing will eliminate the possibility that they could occur, the company said.

Boeing said the software updates will address both issues and that neither new software issue has been observed in flight.

In January, Boeing discovered another software issue relating to a power-up monitoring function that verifies some system monitors are operating correctly.

Boeing says it has made significant progress over the past several months in support of safely returning the 737 MAX to service as the company continues to work with the FAA and other global regulators on the process laid out for certifying the 737 MAX software and related training updates.

The Federal Aviation Administration said on Tuesday it is in contact with Boeing as it “continues its work on the automated flight control system on the 737 MAX. The manufacturer must demonstrate compliance with all certification standards.”