diff --git a/drivers/acpi/power_meter.c b/drivers/acpi/power_meter.c
index e6bfd77..2ef7030 100644
--- a/drivers/acpi/power_meter.c
+++ b/drivers/acpi/power_meter.c
@@ -294,7 +294,11 @@
 		return -EINVAL;
 	}
 
-	return data;
+	/* _PTP returns 0 on success, nonzero otherwise */
+	if (data)
+		return -EINVAL;
+
+	return 0;
 }
 
 static ssize_t set_trip(struct device *dev, struct device_attribute *devattr,