diff --git a/use-shopping-cart/core/Entry.js b/use-shopping-cart/core/Entry.js
index 3b9dca7..74662a9 100644
--- a/use-shopping-cart/core/Entry.js
+++ b/use-shopping-cart/core/Entry.js
@@ -54,6 +54,7 @@ function Entry({ id, product, quantity, price_metadata, product_metadata }) {
     id,
     quantity,
     value: product.price * quantity,
+    timestamp: new Date().toISOString(), // add a timestamp in ISO 8601 format
     price_data: {
       ...product.price_data,
       ...price_metadata