Cart default value can not be 0

-- HikaShop version -- : 6.1.1

Normally the quantity is displayed in the cart button of the cart module. When the card is empty, I would like to show 0 as value. The problem is that the number 0 get ignored. Also when I change the language string CART_EMPTY="The cart is empty" to CART_EMPTY="0" the value is not shown.