diff --git a/core/app/models/spree/shipment.rb b/core/app/models/spree/shipment.rb
index 67203f8e9c0..8e8a9caa230 100644
--- a/core/app/models/spree/shipment.rb
+++ b/core/app/models/spree/shipment.rb
@@ -13,6 +13,7 @@ class Shipment < Spree::Base
     has_many :shipping_methods, through: :shipping_rates
     has_many :state_changes, as: :stateful
     has_many :cartons, -> { distinct }, through: :inventory_units
+    has_many :line_items, -> { distinct }, through: :inventory_units
 
     before_validation :set_cost_zero_when_nil
 
@@ -188,10 +189,6 @@ def item_cost
       line_items.map(&:total).sum
     end
 
-    def line_items
-      inventory_units.includes(:line_item).map(&:line_item).uniq
-    end
-
     def ready_or_pending?
       ready? || pending?
     end