diff --git a/src/superio/nuvoton/npcd378/superio.c b/src/superio/nuvoton/npcd378/superio.c
index 6a56ac8b89..36458329a8 100644
--- a/src/superio/nuvoton/npcd378/superio.c
+++ b/src/superio/nuvoton/npcd378/superio.c
@@ -68,8 +68,8 @@ static void npcd378_init(struct device *dev)
 
 		npcd378_hwm_write_start(res->base);
 
-		int fan_lvl = get_int_option("psu_fan_lvl", -1);
-		if (fan_lvl < 0 || fan_lvl > 7)
+		unsigned int fan_lvl = get_int_option("psu_fan_lvl", 3);
+		if (fan_lvl > 7)
 			fan_lvl = 3;
 
 		uint8_t pwm = NPCD378_HWM_PSU_FAN_MIN +