Multiple Definitions

[bronxbomber92]

I've created a new file, where I keep all of this years code. When I compile my project I get an error saying symbol 'ReleasingBall' has multiple definitions.

Here's how my files are organized:

custom_routines.h

#ifndef _CUSTOM_ROUTINES_H_
#define _CUSTOM_ROUTINES_H_

//...
bool ReleasingBall;
//...
#endif

custom_routines.c

#include <timer.h>
#include "custom_routines.h"

// function definitions

user_routines.h

//..
#include "custom_routines.h" 

// all of my custom code is commented out, so beside the above include directive, everything is in its original state

Why am I getting this error, the include guards should be preventing this problem!