Ltac wlt_ind :=
  match goal with
  | [ |- forall (n: word ?len), ?P ] =>
    refine (well_founded_ind (@wlt_wf len) (fun n => P) _)
  end.

Lemma ZToWord_Z_of_nat: forall sz x, ZToWord sz (Z.of_nat x) = natToWord sz x.