I am trying to install ocaml with a set of libraries on my FreeBSD 7 machine.

So far I have installed ocaml 3.10.2  from FreeBSD ports and I now trying to 
install bin_prot library manually.

make  fails to build the bin-prot with the following error:

gmake[2]: Leaving directory 
`/usr/home/eratosfen/Desktop/ocaml/bin-prot-1.0.5/lib'
ocamlfind ocamlc -package type-conv -c -pp "camlp4orf " -for-pack Bin_prot -I 
+camlp4 pa_bin_prot.ml
File "pa_bin_prot.ml", line 77, characters 19-48:
Unbound value Gen.drop_variance_annotations
gmake[1]: *** [pa_bin_prot.cmo] Error 2
gmake[1]: Leaving directory 
`/usr/home/eratosfen/Desktop/ocaml/bin-prot-1.0.5/lib'


What is Gen.drop_variance_annotations? and why it is absent?