std::mutex missing when building Qt app with MXE gcc

I'm attempting to get a Qt application to build from the command line under linux targetted for windows. I've used mxe to build a toolchain for targetting windows but my build fails whinging about various thread related bits. mxe built with winpthreads and I know the Qt project will build on windows itself from inside of creator, using the pre-packaged mingw compiler. I'm successfully building using my ARM Linux cross compiler, so I just want to get windows done the same. I'm trying to get a one line build on a build server or from Jenkins for all my targets.

I'm guessing I'm missing something that I need to pass to mxe when doing the cross toolchain build or alternatively missing something I need to pass to qmake to for this build to succeed.

via Chebli Mohamed