pkunzip emacs 21.2

[jerry d]

Hi've used emacs 20.7 and I used to be able to unzip class files directly
from a jar into a new buffer and then save this buffer and decompile the
class file. Very convenient.
However lately I upgraded to version 21.2, and everything seemed to work
fine, until I tried to do same as described above. Unfortunately this
failed, because emacs is looking for pkunzip, instead of gunzip which (I
think) was used in the previous version. The free version of pkunzip
promised a built in spy-ware feature with all kinds of nice popups so i
decided to skip that approach.

How can make 21.2 behave the same as "the good old" 20.7 in this matter?

tia
Jeroen.