Hi, I have problems linking my project with jpeg.lib. My current project uses a number of external libraries. So when I combine all together, the compiler complains. This is the error I have got. jpeg.lib(jerror.obj) : error LNK2019: unresolved external symbol __iob referenced in function _output_message I set project properties->C++->Code Generation->Runtime library to Multi-threaded Debug DLL I suspect jpeg.lib was compiled with single-thread. Please help how I can solve this problem. Thank you.