fp looks for a unit System ?

[apologises for possibly wrong english]
Hi, there 

I've installed FreePascal 2.2.0 in my linux home, and I have fp in my
PATH. 
I wish to run gavrasm, an assembler program for AVR microcontrollers
(http://www.avr-asm-tutorial.net/gavrasm/index_de.html),
but I can't
make it to be compiled. Whenever I lauch fp within gavrasm top source
tree or within freepascal installation dir, I've got the same error
message:

	Fatal : can't find unit System used by gavrasm.

Could somebody tell me what's fp exactly looking for, an how could I
help it in getting it ?
-- 
Antonin