build 32-bit library on 64-bit OS

[DFTW]

So I need to build a 32-bit version of a library on 64-bit 
system. I got some errors, which I get rid of after installing 
the gcc 32-bit tools (and gcc -m32 ran fine) but I still get 
errors about libraries not compatible.

the command:
dub --arch=x86

yield erros such:

/usr/bin/ld: skiping 
//usr/lib/x86_64-linux-gnu/libphobos2-ldc-shared.so incompatible 
to -lphobos2-ldc-shared
/usr/bin/ld: couldn't find -lphobos2-ldc-shared
//....
collect2: error: ld returned 1 exit status
Error: /usr/bin/gcc failed with status: 1
/usr/bin/ldc2 failed with exit code 1.

How do I fix this?