All build failing with "cannot find -lGL" from G++ command

Hi Whatever I try to build fails with the above message… in full it is ———————- g++ -Wl,-rpath,/home/laurie/Dev/Qt5.3.2/5.3/gcc_64 -Wl,-rpath,/home/laurie/Dev/Qt5.3.2/5.3/gcc_64/lib -o Countdown2 main.o mainwindow.o moc_mainwindow.o -L/home/laurie/Dev/Qt5.3.2/5.3/gcc_64/lib -lQt5Widgets -lQt5Gui -lQt5Core -lGL -lpthread /usr/bin/ld: cannot find -lGL Makefile:192: recipe for target ‘Countdown2’ failed ————— I can obviously see that the problem is the “-lGL” flag is the issue but I cannot see where this is is configured, or whether I’m actually missing a library somewhere. Can someone please give me some pointers here. This is Qt Creator 3.2.1 Based on Qt 5.3.2 (GCC 4.6.1, 64 bit) Environment is Kubuntu 14.10 Thanks Sam