Hardening suffixes trigger a kind of fortition. Stem-final plain stops or affricates or sonorants become glottalized. As with weakening suffixes, the hardening patterns of fricatives are less predictable. hardens to or . (The classification is apparently arbitrary and not necessarily consistent with the weakening behavior of a given stem; a stem in which becomes when weakened may become either or when it is hardened, etc.) hardens to . Both and harden to , while in a hardening context surfaces with an additional following glottal stop: . hardens to .