compiling d code without phobos ?

[Wiz]

I'm currently working on a little OS, and my goal is to use the D 
language as the main one.
I had no problem to build a running very very primitive version, but 
when I tried to define (not even using it), I have seen some troubles : 
gdc tells me there is a few reference that are undefined.
Right, theses references are the phobos ones : I have no need of since 
phobos can't work on my system yet (memory allocs and lot of things are 
going to be rebuild by myself later).
I then tried to make my own object.d file, I put it into my kernel 
folder and added it to the makefile, I still have some problems...
When compiling my version of object.d containing just a class definition 
'object', gdc seg faults. It seems to me that gdc imports 
mingw/include/d/3.4.5/object.d before compiling mine, and don't know 
what to do in the case of these two.
I also before got a error telling me the class was already defined (but 
don't remember how, from what I know there is no notable difference 
between the yesterdays context, and todays one), that's wy I ask if 
anybody knows any way of not using the phobos object.d, just my own ?
Tried the -nostdlib of gcc, without any positive results.

ps: Using windows version of gdc (GCC) 3.4.5 (mingw special) (gdc 0.19, 
using dmd 0.162)