install postgres8.1 on debian

I'm trying to install postgresql 8.1, from source but I get stuck at the 3
step:

1- ./configure --without-zlib

2- make all

3- make install

(many lines omitted)

make[3]: Leaving directory
`/usr/local/src/postgresql-8.1.4/src/backend/utils/mb/conversion_procs/utf8_
and_win874'

make[2]: Leaving directory
`/usr/local/src/postgresql-8.1.4/src/backend/utils/mb/conversion_procs'

make -C include install

make[2]: Entering directory `/usr/local/src/postgresql-8.1.4/src/include'

mkdir -p -- /usr/local/pgsql/include/libpq
/usr/local/pgsql/include/internal/libpq

mkdir: cannot create directory `/usr/local/pgsql/include': File exists

mkdir: cannot create directory `/usr/local/pgsql/include': File exists

make[2]: *** [installdirs] Error 1

make[2]: Leaving directory `/usr/local/src/postgresql-8.1.4/src/include'

make[1]: *** [install] Error 2

make[1]: Leaving directory `/usr/local/src/postgresql-8.1.4/src'

make: *** [install] Error 2

it's weird because it's the first time I installed it.

iuri