diff --git a/drivers/acpi/battery.c b/drivers/acpi/battery.c
index 5fdfe65fe165..8ec8a89a20ab 100644
--- a/drivers/acpi/battery.c
+++ b/drivers/acpi/battery.c
@@ -695,7 +695,7 @@ static void acpi_battery_quirks(struct acpi_battery *battery)
 	if (battery->power_unit && dmi_name_in_vendors("LENOVO")) {
 		const char *s;
 		s = dmi_get_system_info(DMI_PRODUCT_VERSION);
-		if (s && !strnicmp(s, "ThinkPad", 8)) {
+		if (s && !strncasecmp(s, "ThinkPad", 8)) {
 			dmi_walk(find_battery, battery);
 			if (test_bit(ACPI_BATTERY_QUIRK_THINKPAD_MAH,
 				     &battery->flags) &&