diff --git a/hw/qdev.c b/hw/qdev.c
index 689cf4cf930eac41edaac8e1e984c8ff68909e66..636dc78e599bc1c51f257be69e99ea601a5c24fd 100644
--- a/hw/qdev.c
+++ b/hw/qdev.c
@@ -49,7 +49,7 @@ struct DeviceType {
 };
 
 /* This is a nasty hack to allow passing a NULL bus to qdev_create.  */
-BusState *main_system_bus;
+static BusState *main_system_bus;
 
 static DeviceType *device_type_list;