This article concerns the use of a matched-guise task in a language documentation project, showing how such a perceptual tool can be used to highlight ongoing language change and attitudes towards an endangered language. Baba Malay, an endangered creole spoken by the Peranakans, has two forms of words encoding coarseness or refinedness. Words ending with [-al], [-a[[voiced alveolar tap or flap]], and [-as], such as [tampal] 'mend', [baka[voiced alveolar tap or flap]] 'burn', and [nanas] 'pineapple' are recognized by speakers as kasar 'coarse', in contrast to alus 'refined' forms ending with [-[open-mid front unrounded vowel]], such as [tamp[open-mid front unrounded vowel]] 'mend', [bak[open-mid front unrounded vowel]] 'burn', and [nan[open-mid front unrounded vowel]] 'pineapple'. Language documentation work shows younger and less proficient speakers producing less refined forms than older and more proficient speakers. No such trend is found for coarse forms. A matched-guise task incorporated into a language documentation project shows that younger community members perceive the refined form as being more emblematic of the Peranakan language, culture, and community. In addition to results that highlight the ongoing language change, the implication is that quantitative perceptual work and language documentation are highly complementary.