$(CSC) -t:exe -r:../IronPython.dll -t:winexe -define:IRONPYTHON_WINDOW -out:../ipyw.exe -recurse:IronPythonConsole/*.cs has two -t options. Better: $(CSC) -t:winexe -r:../IronPython.dll -define:IRONPYTHON_WINDOW -out:../ipyw.exe -recurse:IronPythonConsole/*.cs Seo Sanghyeon