Hi ivar, Do not define external linkage variables in header files. Declaring them is fine; defining them is not. Keeping in mind that the terms "declare" means it generates no bytes (more or less) of code or data, and "define" *does* produce bytes. Byte producing declarations (code or data) should be in .cpp files, not .h files. If you do put the variable's definition in the header file, that means you cannot include that header file in any other translation unit that is linked together. If you tried, you'd get multiple definitions of the same variable. Just as you are seeing. It appears you included (directly or indirectly) your header file in both ibroker.o and imaker5.o. HTH, --Eljay
