diff --git a/erpnext/buying/doctype/purchase_order/purchase_order.py b/erpnext/buying/doctype/purchase_order/purchase_order.py
index b830e7d..32b73dd 100644
--- a/erpnext/buying/doctype/purchase_order/purchase_order.py
+++ b/erpnext/buying/doctype/purchase_order/purchase_order.py
@@ -640,6 +640,7 @@
 				update_sco_status(sco, "Closed" if self.status == "Closed" else None)
 
 
+@frappe.request_cache
 def item_last_purchase_rate(name, conversion_rate, item_code, conversion_factor=1.0):
 	"""get last purchase rate for an item"""