diff --git a/drivers/hwmon/gpio-fan.c b/drivers/hwmon/gpio-fan.c
index 3104149795c5..ce1d82762ba6 100644
--- a/drivers/hwmon/gpio-fan.c
+++ b/drivers/hwmon/gpio-fan.c
@@ -172,7 +172,7 @@ static int get_fan_speed_index(struct gpio_fan_data *fan_data)
 	return -EINVAL;
 }
 
-static int rpm_to_speed_index(struct gpio_fan_data *fan_data, int rpm)
+static int rpm_to_speed_index(struct gpio_fan_data *fan_data, unsigned long rpm)
 {
 	struct gpio_fan_speed *speed = fan_data->speed;
 	int i;