  Starquakes are considered for fast-rotating magnetic white dwarfs. The X-ray
pulsar 1E 2259 + 586 may be such a white dwarf. It is shown that in this case
starquakes may be responsible for the decrease of the mean spin-down rate which
was observed for 1E 2259 + 586 between 1987 and 1990. The required mass of the
white dwarf which is identified with 1E 2259 + 586 is $\sim 1.4 - 1.5 M_\odot$,
making this X-ray pulsar the most massive white dwarf known.
