--- peripherals/sim_5307.c.orig	Thu Feb 18 08:05:34 2021
+++ peripherals/sim_5307.c	Thu Feb 18 08:05:50 2021
@@ -59,7 +59,7 @@
 static struct _sim_register *sim_register_lookup_by_name(char *name);
 static void sim_interrupt_assert(s16 number, s16 vector);
 static void sim_interrupt_withdraw(s16 number);
-struct _sim sim_data;
+extern struct _sim sim_data;
 
 /* name, offset, width, read, write, resetvalue, description */
 static struct _sim_register sim_reg[] = {