The chief executive of Guinness-owner Diageo has stepped down with immediate effect, the drinks giant has announced. In an unusual move for a big corporation, Debra Crew has left her role without a succession plan in place. The firm is looking for a replacement, and in the meantime chief financial officer Nik Jhangiani will take on her role.

Diageo, the world’s biggest spirits maker, announced Wednesday that CEO Debra Crew is stepping down by “mutual agreement” after just two years in the role.

Diageo CEO Debra Crew resigned as the maker of brands including Smirnoff vodka and Guinness beer struggles with weak sales.