Non-prefixed static builds of Qt default to linux paths on Windows during configure

When configuring static build of Qt and not using prefix, the default paths are Linux paths. After configure, the following message can be seen:
Qt will be installed into '\usr\local\Qt-5.9.1'.

The used configure command can be simple as:
configure -static -commercial -confirm-license -nomake tests -nomake examples

When using the qmake from this build, qt modules cannot be found, qmake debug gives this kind of log:
DEBUG 1: C:/Qt/5.9.1/Src/qtbase/mkspecs/features/qt_config.prf:26: QT_MODULE_INCLUDE_BASE := /usr/local/Qt-5.9.1/include
DEBUG 1: C:/Qt/5.9.1/Src/qtbase/mkspecs/features/qt_config.prf:27: QT_MODULE_LIB_BASE := /usr/local/Qt-5.9.1/lib
DEBUG 1: C:/Qt/5.9.1/Src/qtbase/mkspecs/features/qt_config.prf:28: QT_MODULE_HOST_LIB_BASE := /usr/local/Qt-5.9.1/lib
DEBUG 1: C:/Qt/5.9.1/Src/qtbase/mkspecs/features/qt_config.prf:29: QT_MODULE_BIN_BASE := /usr/local/Qt-5.9.1/bin

Using prefix in configure fixes this issue.