In both cases, you should have two versions of Qt installed: The native one and Qt embedded. The application that shall run inside the qvfb has to be linked against Qt embedded, not the native version. From your description, it looks like your application is linked agains the native Qt. When installing two versions of Qt, be sure to invoke the right qmake that was built together with that particular version of Qt, e.g. run qmake from Qt embedded before compiling your application. This will make sure the generated Makefile links agains that version of Qt.