Explicit LOAD and dynamic library loading

Hello,

I'm working on two extensions, call them "foo" and "bar". bar depends on
some of the functions defined in foo. They are both built from a single
Makefile, just vanilla PGXS:

MODULES = foo bar
EXTENSION = foo bar
### etc. ###

As bar depends on foo, that's specified in its .control file, and CREATE
EXTENSION works just fine with foo created first, then bar.

However, whenever I run one of the UDTs defined in bar, I get this error
message:

dev=# SELECT * FROM test1 WHERE (info(bar_dat)).some_prop = 10;
ERROR: could not load library
"/vol/data/home/postgres/pg-builds/9.2.4/lib/bar.so":
/vol/data/home/postgres/pg-builds/9.2.4/lib/bar.so: undefined symbol:
foo_func1

I have to explicitly load foo:

dev=# LOAD 'foo.so';

Then everything works. What am I missing?

Thanks.