In modern Turkish, the apostrophe is used to separate proper names from inflectional endings (İzmir’de ‘in İzmir’). This is not the case with inflected common nouns (şehirde ‘in the city’). In this respect, the apostrophe constitutes an instance of graphematic dissociation between proper names and common nouns. Interestingly, the apostrophe was originally employed to transliterate hamza and ayn in Arabic and Persian loanwords (san’at ‘art’). However, these loanwords gradually lost the apostrophe (sanat ‘art’). This implies that Turkish experienced a graphematic change whereby the apostrophe developed from a phonographic marker of glottal stop into a morphographic marker of morpheme boundaries in proper names. This refunctionalization process is illustrated by a diachronic corpus analysis based on selected issues of the newspaper Cumhuriyet from 1929–1975. The findings reveal that the use of the apostrophe with proper names was triggered by foreignness. More specifically, the apostrophe first occurred with foreign names to highlight morpheme boundaries (Eden’in ‘of Eden’) and then expanded to native names via animacy (Doğan’ın ‘of Doğan’).