I investigate the distribution of the morpheme qu in Squliq Atayal (Formosan). Qu normally marks the sentence-final subject, which is cross-referenced by voice morphology on the verb. I show that qu can optionally mark specific, non-subject arguments in cases where the actual subject is not in sentence-final position. I propose that qu is a marker on topics licensed in a particular structural position (Spec,TopicP). While the subject will normally be in this position, when it is not, another [+specific] DP can occupy this position and be qu-marked. Consequences for theories of Austronesian voice will be discussed.