 If either of the two was voiceless, the whole cluster was devoiced, and the first obstruent also lost its labialisation, if it was present.Most examples of this occurred with obstruents preceded by *s (resulting in *sp, *st, *sk, *skʷ), or obstruents followed by *t (giving *ft, *ss, *ht, *ht) or *s (giving *fs, *ss, *hs, *hs).The latter change was frequent in suffixes, and became a phonotactic restriction known as the Germanic spirant law.