diff --git a/arch/x86/kernel/ksysfs.c b/arch/x86/kernel/ksysfs.c
index eb53d153f307..c2bedaea11f7 100644
--- a/arch/x86/kernel/ksysfs.c
+++ b/arch/x86/kernel/ksysfs.c
@@ -17,6 +17,7 @@
 #include <linux/slab.h>
 #include <linux/mm.h>
 
+#include <asm/io.h>
 #include <asm/setup.h>
 
 static ssize_t version_show(struct kobject *kobj,