> 100% pure SeaHash does x ^= t at the start first, instead of `t ^ (t << 1)` on the RHS. Indeed. Some initial testing shows that this kind of "input mangling" (applying such a permutation on the inputs) actually plays a much more important role to avoid collisions than the SeaHash operation x ^= ((x >> 16) >> (x >> 29)). So my suggestion remains for y in INPUT: t = hash(y) t ^= t * SOME_LARGE_EVEN_NUMBER h ^= t h *= MULTIPLIER Adding in the additional SeaHash operations x ^= ((x >> 16) >> (x >> 29)) x *= MULTIPLIER does not increase the probability of the tests passing.