The genitive of the Turkish noun ''su''

The declension table for the Turkish noun su (water), using the template call {{tr-infl-noun-v|u}}, lists its genitive as sunun. The genitive of su is, however, actually suyun.
    This is one of the very rare exceptions in Turkish; su is the only word in which the regular buffer consonant n between vowels is replaced by the consonant y. It also applies to the possessives; e.g., the 3rd-person-singular is suyu, not *sunu. Examples: suyun tadı = "the taste of water"; maden suyu = "mineral water".
    Can you think of a way to fix this, so that the correct form is displayed?

Rua has quit the project. You'd do better to ask at WT:GP.