diff --git a/drivers/acpi/dock.c b/drivers/acpi/dock.c
index 811b1aac65d566f9c215f926d2987db2a384b5ff..4546bf873aea273c2a0993fb3fbb465d801543ed 100644
--- a/drivers/acpi/dock.c
+++ b/drivers/acpi/dock.c
@@ -29,6 +29,7 @@
 #include <linux/notifier.h>
 #include <linux/platform_device.h>
 #include <linux/jiffies.h>
+#include <linux/stddef.h>
 #include <acpi/acpi_bus.h>
 #include <acpi/acpi_drivers.h>
 
@@ -674,7 +675,7 @@ static ssize_t show_dock_uid(struct device *dev,
 			     struct device_attribute *attr, char *buf)
 {
 	unsigned long lbuf;
-	acpi_status status = acpi_evaluate_integer(dock_station->handle, "_UID", 0, &lbuf);
+	acpi_status status = acpi_evaluate_integer(dock_station->handle, "_UID", NULL, &lbuf);
 	if(ACPI_FAILURE(status)) {
 	    return 0;
 	}