diff --git a/src/include/gpxe/settings.h b/src/include/gpxe/settings.h
index 78f3e698..ee7dacee 100644
--- a/src/include/gpxe/settings.h
+++ b/src/include/gpxe/settings.h
@@ -216,6 +216,7 @@ extern struct setting priority_setting __setting;
 extern struct setting bios_drive_setting __setting;
 extern struct setting uuid_setting __setting;
 extern struct setting next_server_setting __setting;
+extern struct setting mac_setting __setting;
 
 /**
  * Initialise a settings block