Nikola Corp. said Chairman Steve Girsky will take over as its chief executive officer, replacing Michael Lohscheller after less than a year in the role atop the maker of electric trucks.

Lohscheller is stepping down immediately from the executive post “due to a family health matter and will be returning to Europe,” Nikola said Friday in a statement. He’ll depart the board at the end of the month and will remain in an advisory capacity through September.

Shares of Nikola rose 1.6% in premarket trading to $3.45 as of 8:04 a.m. in New York.