Dear Maintainer, I noticed that on Debian Trixie with QT_SELECT=6 set, qmake is complaining "qmake: could not find a Qt installation of '6'" because qtchooser does not know Qt 6. The only thing which would be needed is to add 6.conf and qt6.conf files in /usr/lib/x86_64-linux-gnu/qtchooser/, which is done in debian/rules. In Debian Trixie, it would probably be better to have Qt 6 as the default rather then 5 (i.e. "qtchooser -qt=default -print-env" should print variables for Qt 6).