  Let $L$ be a lattice. We call a congruence relation $\gQ$ of $L$ isoform, if
any two congruence classes of $\gQ$ are isomorphic (as lattices). Let us call
the lattice $L$ isoform, if all congruences of $L$ are isoform.
  G. Gr\"atzer and E.\,T. Schmidt proved that every finite distributive lattice
$D$ can be represented as the congruence lattice of a finite isoform lattice
$L$.
  We now prove that every finite lattice $K$ has a congruence-preserving
extension to a finite isoform lattice $L$.
