I need some headers from the dev-version of postgres 9, which is contained in libpq-dev, for installing the pg gem, but when I execute: sudo apt-get install libpq-dev I get the result: The following packages have unmet dependencies: libpq-dev : Depends: libpq5 (= 8.4.7-0ubuntu0.10.10) but 9.0.1-1~lucid is to be installed When I tried to remove libpq5 (to reinstall it correctly?), it threatened to remove postgresql-9.0: The following packages will be REMOVED: libpq5 pgadmin3 php5-pgsql postgresql-9.0 postgresql-client-9.0 Does anybody know how to solve this problem? Thanks.