import prefers module in package over local module

Hello *, I am migrating a project from ghc 6.2 to ghc 6.4. This project has a module called Pretty and that's where my problems start. When importing Pretty, ghc does not consider my local definition but the Pretty module from the standard library (which is an alias for Text.PrettyPrint.HughesPJ). Is this behaviour intended or is it a bug? Can I change it? If it is intended, can somebody explain the rationale to me? BTW, I am using -hidir and -odir and the latest Debian package containing ghc 6.4.1. Thank you, Michael