diff --git a/src/Cart.php b/src/Cart.php
index 3eb9ede..4d3bbcc 100644
--- a/src/Cart.php
+++ b/src/Cart.php
@@ -516,7 +516,7 @@ class Cart
      *
      * @return void
      */
-    public function setGlobalDiscount($discount): void
+    public function setGlobalDiscount(float $discount): void
     {
         $this->discount = $discount;