This study is designed to evaluate repeat doses of isavuconazole on cardiac repolarization in healthy adult subjects. Eligible subjects will be randomized to one of four treatment groups and be confined for 17 days including pre-dosing days. Moxifloxacin will be given as an active control on the last dosing day to healthy subjects in one of the four groups. All treatments, except the moxifloxacin dose, are double-blinded (neither the subject nor the study doctor will know the treatment assignment). Subjects will undergo continuous ECGs on three study days. ECGs, vital signs, blood draws will be obtained throughout the study for safety and to assess the amount of study drug in body.