Sysroot in QT4

[Radim]

Hi,

I want to cross-compile an application using Qt Creator. I created Kit for the cross compiler/QT4 and have setup sysroot path in the kit. I want to modify the qmake.conf in mkspecs dir to use the sysroot path from Qt Creator. Up to now I used an environment variable that I used in the qmake.conf but I would like to get rid of this dependency. I tried
QMAKE_INCDIR = $$[QT_SYSROOT]/usr/include
but it does not work. I suppose it works only in QT5. Is there an alternative for sysroot in QT4?