you have e.g.
unsigned int Ralph
in your .h file

if so, it will be defined in both modules.

you will need to define it in one and declare it in the other

e.g.
in one
unsigned int Ralph
in the other
extern unsigned int Ralph

my method is as follows
in the .h
#ifdef MAIN_MODULE
#define DOC extern
#else
#define DOC
#endif

DOC unsigned int Ralph

then in one and only one module
#define MAIN_MODULE

please do not ask where DOC comes from, it was done long ago and I am actually puzzled what it means, however "a rose with any other name ..."

I know the opinion on this method is split, some use it, some have disdain for it

Erik

...replace this with your code...