diff --git a/make_post_sell/models/cart.py b/make_post_sell/models/cart.py
index b3ccbe0..a751036 100644
--- a/make_post_sell/models/cart.py
+++ b/make_post_sell/models/cart.py
@@ -300,7 +300,6 @@ class Cart(RBase, Base):
                 )
         return self._discounted_shop_totals
 
-
     @property
     def total_price_in_cents(self):
         """
@@ -456,7 +455,27 @@ class Cart(RBase, Base):
             elif self.handling_option == "local_shipping":
                 self.handling_cost_in_cents = shop_location.local_shipping_rate_in_cents
             elif self.handling_option == "international_shipping":
-                self.handling_cost_in_cents = shop_location.international_shipping_rate_in_cents
+                self.handling_cost_in_cents = (
+                    shop_location.international_shipping_rate_in_cents
+                )
+
+    def update_inventory(self, shop_location):
+        """
+        Update the inventory quantity for physical products in the cart.
+        """
+        changed = False
+        for product_id, product in self.physical_products.items():
+            quantity_needed = self.cart[product_id]
+            inventory = get_inventory_by_product_and_shop_location(
+                self.dbsession, product_id, shop_location.uuid_str
+            )
+            if inventory:
+                inventory.quantity -= quantity_needed
+                self.dbsession.add(inventory)
+                changed = True
+
+        if changed:
+            self.dbsession.flush()
 
 
 def get_all_carts(dbsession):
diff --git a/make_post_sell/models/invoice.py b/make_post_sell/models/invoice.py
index 8e13efc..9246142 100644
--- a/make_post_sell/models/invoice.py
+++ b/make_post_sell/models/invoice.py
@@ -202,7 +202,7 @@ class Invoice(RBase, Base):
     def total_in_cents(self):
         """Calculate the total amount in cents for the invoice, including handling fee."""
         line_items_total = sum(
-            item.price_in_cents * item.quantity for item in self.line_items
+            item.price.price_in_cents * item.quantity for item in self.line_items
         )
         return line_items_total + (self.handling_cost_in_cents or 0)
 
diff --git a/make_post_sell/views/cart.py b/make_post_sell/views/cart.py
index 17285ce..5946390 100644
--- a/make_post_sell/views/cart.py
+++ b/make_post_sell/views/cart.py
@@ -465,6 +465,7 @@ def cart_complete_checkout(request):
         for shop_id, product_quantity_tuple in cart.shop_product_dict.items():
             shop = cart.shops[shop_id]
             invoice = Invoice(user=request.user)
+            invoice.shop = shop
             invoice.shop_id = shop.id
             invoice.handling_option = cart.handling_option
             invoice.handling_cost_in_cents = cart.handling_cost_in_cents
@@ -522,6 +523,9 @@ def cart_complete_checkout(request):
                     break
 
         if successful_checkout:
+            # Update inventory for physical products
+            cart.update_inventory(request.shop_location)
+
             # flush changes to database because charge was successful!
             request.dbsession.flush()
             msg = ("Success, you have completed the purchase!", "success")