diff --git a/drivers/char/n_tty.c b/drivers/char/n_tty.c
index 46b2a1c..0c09409 100644
--- a/drivers/char/n_tty.c
+++ b/drivers/char/n_tty.c
@@ -1183,7 +1183,7 @@
 	return retval;
 }
 
-extern ssize_t redirected_tty_write(struct file *, const char *,
+extern ssize_t redirected_tty_write(struct file *, const char __user *,
 							size_t, loff_t *);
 
 /**