diff --git a/cargo-elevator.lua b/cargo-elevator.lua
index 66749bb..6aadb4b 100644
--- a/cargo-elevator.lua
+++ b/cargo-elevator.lua
@@ -98,7 +98,7 @@ local PKG_QUEUE = {
     end,
     check_cargo = function (self, inv, floors)
         for slot, item in pairs(peripheral.call(inv, "list")) do
-            local item_detail = peripheral.call(src, "getItemDetail", slot)
+            local item_detail = peripheral.call(inv, "getItemDetail", slot)
             for i, floor in ipairs(floors) do
                 if item_detail.package ~= nil and
                     floor.match(item_detail.package.getAddress()) then