extern const char* const SOME_CONSTANT giving me linker errors

most probably you forgot to include your header in your implementation file

anyway, add the keyword extern to the definition

without an extern declaration it has internal linkage and is thus not visible to the linker

The problem could be that the extern declaration is not visible in the source file defining the constant. Try repeating the declaration above the definition, like this:

extern const char* const SOME_CONSTANT;  //make sure name has external linkage
const char* const SOME_CONSTANT = "test";  //define the constant