Although the change of *t to k in Hawaiian has been known and commented on for over 150 years, the widespread driftlike character of this development within Austronesian as a whole has generally gone unappreciated. This paper examines 20 historically independent instances of a *t > k change in at least 43 languages. Twelve of these changes are confined to Oceanic languages, seven to languages of eastern Indonesia, and one to western Indonesia. Almost without exception, the change *t > k has followed the loss of *k. In four languages *t > k took place only word-finally, and in two others it appears to be dissimilatory. Both structural and perceptual motivations for the change are considered, and it is concluded that *t > k usually begins as free variation within an enlarged phonological space created by the loss of *k. A few instances are difficult to reconcile with this explanation, and continue to present a challenge to linguistic theory.