diff --git a/src/methods/add-item.js b/src/methods/add-item.js
index fcede32..c61df27 100644
--- a/src/methods/add-item.js
+++ b/src/methods/add-item.js
@@ -53,11 +53,12 @@ export default ({ data, save }, emitter, [newItem, canSave = false]) => {
   }
 
   if (!fixedItem) {
+    const itemCopy = Object.assign({}, newItem)
     if (!newItem._id || newItem._id === newItem.variation_id) {
-      newItem._id = randomObjectId()
+      itemCopy._id = randomObjectId()
     }
-    data.items.push(newItem)
-    fixedItem = fixItemQuantity(newItem)
+    data.items.push(itemCopy)
+    fixedItem = fixItemQuantity(itemCopy)
   }
   fixSubtotal(data)