diff --git a/drivers/hwmon/max6650.c b/drivers/hwmon/max6650.c
index 86142a858238..58f66be61b1f 100644
--- a/drivers/hwmon/max6650.c
+++ b/drivers/hwmon/max6650.c
@@ -418,6 +418,7 @@ static ssize_t set_div(struct device *dev, struct device_attribute *devattr,
 		data->count = 3;
 		break;
 	default:
+		mutex_unlock(&data->update_lock);
 		dev_err(&client->dev,
 			"illegal value for fan divider (%d)\n", div);
 		return -EINVAL;