diff --git a/drivers/s390/cio/css.c b/drivers/s390/cio/css.c
index 51eaed0d76624358c731420acd27de909b71761a..c47b25fd3f438b32cc19c5cdeeb2dd63287d56a2 100644
--- a/drivers/s390/cio/css.c
+++ b/drivers/s390/cio/css.c
@@ -35,6 +35,7 @@ int css_init_done = 0;
 int max_ssid;
 
 struct channel_subsystem *channel_subsystems[__MAX_CSSID + 1];
+static struct bus_type css_bus_type;
 
 int
 for_each_subchannel(int(*fn)(struct subchannel_id, void *), void *data)
@@ -1214,7 +1215,7 @@ static const struct dev_pm_ops css_pm_ops = {
 	.restore = css_pm_restore,
 };
 
-struct bus_type css_bus_type = {
+static struct bus_type css_bus_type = {
 	.name     = "css",
 	.match    = css_bus_match,
 	.probe    = css_probe,
@@ -1251,4 +1252,3 @@ void css_driver_unregister(struct css_driver *cdrv)
 EXPORT_SYMBOL_GPL(css_driver_unregister);
 
 MODULE_LICENSE("GPL");
-EXPORT_SYMBOL(css_bus_type);
diff --git a/drivers/s390/cio/css.h b/drivers/s390/cio/css.h
index 566dc1ac425e61a2b37e833fe2447a8ae873c4cd..80ebdddf7747a4b24c7ab4d07b1f952a3a257e39 100644
--- a/drivers/s390/cio/css.h
+++ b/drivers/s390/cio/css.h
@@ -97,11 +97,6 @@ struct css_driver {
 
 #define to_cssdriver(n) container_of(n, struct css_driver, drv)
 
-/*
- * all css_drivers have the css_bus_type
- */
-extern struct bus_type css_bus_type;
-
 extern int css_driver_register(struct css_driver *);
 extern void css_driver_unregister(struct css_driver *);
 
@@ -136,7 +131,6 @@ struct channel_subsystem {
 };
 #define to_css(dev) container_of(dev, struct channel_subsystem, device)
 
-extern struct bus_type css_bus_type;
 extern struct channel_subsystem *channel_subsystems[];
 
 /* Helper functions to build lists for the slow path. */