--- a/./src/interface.h
+++ b/./src/interface.h
@@ -21,8 +21,8 @@
  * Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
  */
 
-int interface_auto_up;
-int interface_do_message;
+extern int interface_auto_up;
+extern int interface_do_message;
 
 typedef enum { IFSTATUS_UP, IFSTATUS_DOWN, IFSTATUS_ERR } interface_status_t;