African leaders Friday appointed Zimbabwean President Robert Mugabe as the new chairman of the 54-nation African Union.

The 90-year-old Mugabe, who has ruled his country since 1980, succeeds Mauritania’s President Mohamed Ould Abdel Aziz.

The announcement was made during the African Union’s two-day heads of state summit at the organization’s headquarters in Ethiopia’s capital.

Traditionally, the chairmanship is given to the leader of the country hosting the next summit, but exceptions have been made as in 2005 when it was the turn of Sudan’s Omar al-Bashir but African leaders bowed to international pressures in the uproar over killings in Darfur. They passed over al-Bashir and instead kept Nigeria’s Olusegun Obasanjo for a second year.

Mugabe defeated rival Morgan Tsvangirai in a 2013 vote marked by allegations of irregularities. Mugabe’s victory ended an uneasy power-sharing deal with the opposition, but foreign investors have been deterred by concerns about corruption and government policies to force foreign-owned and white-owned businesses to cede 51 percent of their shares to black Zimbabweans. Hundreds of manufacturing companies have closed in the past year.