--- a/main.c

+++ b/main.c

@@ -45,11 +45,11 @@ extern VOID f_exit();

 #ifdef KR_headers

 extern VOID f_init(), sig_die();

-extern int MAIN__();

+extern int MAIN__() __attribute__((weak));

 #define Int /* int */

 #else

 extern void f_init(void), sig_die(const char*, int);

-extern int MAIN__(void);

+extern int MAIN__(void) __attribute__((weak));

 #define Int int

 #endif