I'm not sure what this means, can someone point me at what may need = fixing? ilasm -out:vararg.exe vararg.il Assembling 'vararg.il' , no listing file, to exe --> 'vararg.exe' ** (/opt/mono/bin/ilasm.exe:5586): WARNING **: Missing method .ctor in = assembly /opt/mono/bin/ilasm.exe typeref index 98