diff --git a/drivers/acpi/battery.c b/drivers/acpi/battery.c
index cfdef4c1d097a..b4580b2e8706f 100644
--- a/drivers/acpi/battery.c
+++ b/drivers/acpi/battery.c
@@ -651,7 +651,7 @@ static LIST_HEAD(acpi_battery_list);
 static LIST_HEAD(battery_hook_list);
 static DEFINE_MUTEX(hook_mutex);
 
-void __battery_hook_unregister(struct acpi_battery_hook *hook, int lock)
+static void __battery_hook_unregister(struct acpi_battery_hook *hook, int lock)
 {
 	struct acpi_battery *battery;
 	/*