diff --git a/src/LukeSnowden/GoogleShoppingFeed/Item.php b/src/LukeSnowden/GoogleShoppingFeed/Item.php
index b6de24e..ba1f6b6 100644
--- a/src/LukeSnowden/GoogleShoppingFeed/Item.php
+++ b/src/LukeSnowden/GoogleShoppingFeed/Item.php
@@ -14,6 +14,8 @@ class Item
     const OUTOFSTOCK      = 'out of stock';
 
     const PREORDER        = 'preorder';
+    
+    const BACKORDER       = 'backorder';
 
     const BRANDNEW        = 'new';