How to suppress warnings for file included from header

I use GCC -Weffc++ option in my Qt project. To suppress warnings from Qt headers i add QMAKE_CXXFLAGS += -isystem $(QTDIR)\include.
But this doesn't suppress all warnings, i still get annoying warnings from QUuid class because $(QTDIR)\include\QtCore\quuid.h
file includes
..\..\src\corelib\plugin\quuid.h.
I tried to add
QMAKE_CXXFLAGS += -isystem $(QTDIR)\src
and
QMAKE_CXXFLAGS += -isystem $(QTDIR)\src\corelib\plugin
but it didn't help. Is there a way to fix this?