In the present paper an early article of Munkácsi Bernát (1902) is revisited in which he argued in favour of treating the south-western Karaim dealveo-larisation process as a proof of an alleged alternation of alveolar and den-tal affricates and fricatives in the language of the Codex Comanicus. As a next step, Munkácsi (1902) argued that this particular feature is reflected in the language of Csángós (in some varieties of which š, ž is replaced with s, z, respectively), which served, in turn, as an argument in favour of their al-leged Cuman origin. And even though Munkácsi’s orthographic arguments concerning such a change in the Codex Comanicus were convincingly re-jected by Melich (1903), Grønbech (1942), and Räsänen (1949), it has be-en never proved that the Karaim dealveolarisation is not an inherited fea-ture. In this article, therefore, the latest philological researches of Halych Karaim manuscripts from the 18th and the 19th century are presented from which it clearly transpires that the at least the š > s process took place in Karaim in the last decades of the 18th century, so it has nothing in common either with the language of Codex Comanicus or with the Hungarian dia-lect of Csángós.