Hi, I was under the impression that -isystem was used for system header includes and -I was used for non system includes. I am using g++ Thread model: posix gcc version 4.3.0 20070430 (experimental) and when I am not using -isystem (using -I) everything is OK. When I use -isystem I get missing includes from the c++ 4.3.0 stl headers. Do I have to specifically include the c++ headers in the include line when using -isystem? Regards, JT