Hi, I try to use the program_options library in a cygwin environment by compiling my application with the -mno-cygwin -mwindows compiler flag. This flag should lead to a pure windows application. I have boost libraries version 1.33 installed(via http://cygwin.com/). I link my application against libboost_program_options-gcc-mt-s which is sufficient under Linux. However under cygwin I get an undefined reference to `_environ' linker error. I did nm /usr/lib/libc.a | grep _environ and got 00000004 B _environ 00000000 I __imp____cygwin_environ 00000000 I __nm____cygwin_environ (but my build environment[GNU Builds tools] seems to ignore the -lc flag at the linker option line) Has someone experience with this library under cygwin/mingw ? Thomas --