Ubuntu make xconfig qt error

When you do make xconfig (graphical kernel config), you may receive following error

gideon@gideon-desktop:~/linux$ make xconfig
CHECK qt
* Unable to find the QT4 tool qmake. Trying to use QT3
*
* Unable to find any QT installation. Please make sure that
* the QT4 or QT3 development package is correctly installed and
* either qmake can be found or install pkg-config or set
* the QTDIR environment variable to the correct location.

In Ubuntu, you just need to install the qt4-dev-tools package to fix it.

# aptitude install qt4-dev-tools