QtWebEngine bootstrap.py build issue with space in build folder

My Qt src directory is C:\qt5.9. My build directory is C:\qt5.9 build. My -prefix install directory is C:\qt5.9 build\installfolder

When It got to building QtWebEngine I ran into the following error:

bootstrap.py error: Unrecognized command line arguments: build/qtwebengine/src/3rdparty/ninja/ninja.exe.

Project ERROR: GN build error!

It seems if you have a space in your build path, it does not like that! I modified my build path to C:/qt5.9build and the error went away