RubyMine does not 'recognize' the pg gem as the attached PostgreSQL gem

I'm currently working on a project which uses a PostgreSQL DB as backend. Everytime I open this project in RubyMine, RubyMine complains as follows: 'Gems required for project are not attached: postgres'. I've tried manually attaching the pg gem, but RubyMine still complains about it missing 'postgres'. As far as I know, the pg gem actually supersedes the older postgres gem. I know I can suppress 'missing gem' notifications, but I'd rather not.

I'm running RubyMine build 1364, the build environment contains Ruby 1.8.7, Rails 2.3.3, rubygems 1.3.2 and pg 0.8.0.