Retired Marine General James Mattis will step down from his position at General Dynamics Corp. and give up unvested equity awards if confirmed as President-elect Donald Trump’s defense secretary, according to a letter submitted to the Defense Department’s ethics lawyer.

In a letter dated Jan. 5 and made public Saturday, Mattis said that he would resign from the board of General Dynamics board and temporarily recuse himself from matters related to the company, the fifth-biggest U.S. defense supplier with $10 billion in contracts last year.

“For a period of one year after my resignation, I will not participate personally and substantially in any particular matter involving specific parties in which I know General Dynamics is a party or represents a party,” unless he is authorized to participate, Mattis said. Federal regulations allow for such authorization when it’s determined that the government’s interest in an official’s participation outweighs any reasonable concern related to ethics questions.

Mattis also said he will forfeit all restricted stock and stock options in the company “that have not, as of the date of my appointment, vested according the normal schedule for vesting.” Mattis currently holds unvested stock options and restricted shares in General Dynamics worth about $523,000 as of Friday’s close.

In addition, within 90 days of his confirmation he will divest all of his stock and vested stock options from General Dynamics, the letter said. His vested equity awards were worth about $562,000 as of Friday’s close.

Mattis’s confirmation hearing is scheduled Jan. 12 before the Senate Armed Services Committee. As a General Dynamics director since August 2013, Mattis has received at least $276,000 in fees.

The retired general also says he’ll resign from the Hoover Institution, where he’s a visiting fellow. The think tank, which is affiliated with Stanford University, had touted its ties to Mattis and other members of Trump’s transition team in a fund-raising appeal to potential donors last month. A Hoover spokeswoman said Mattis got no advanced copy of the fund-raising message and wasn’t asked to approve it.