diff --git a/drivers/s390/cio/css.c b/drivers/s390/cio/css.c
index dfca0ef139fd..eb08d63b3dac 100644
--- a/drivers/s390/cio/css.c
+++ b/drivers/s390/cio/css.c
@@ -109,7 +109,7 @@ css_subchannel_release(struct device *dev)
 	}
 }
 
-int css_sch_device_register(struct subchannel *sch)
+static int css_sch_device_register(struct subchannel *sch)
 {
 	int ret;
 
diff --git a/drivers/s390/cio/css.h b/drivers/s390/cio/css.h
index ed7977531c3f..5d65e83ca66e 100644
--- a/drivers/s390/cio/css.h
+++ b/drivers/s390/cio/css.h
@@ -139,7 +139,6 @@ struct css_driver {
  */
 extern struct bus_type css_bus_type;
 
-extern int css_sch_device_register(struct subchannel *);
 extern void css_sch_device_unregister(struct subchannel *);
 extern struct subchannel * get_subchannel_by_schid(struct subchannel_id);
 extern int css_init_done;