diff --git a/erpnext/buying/doctype/purchase_order/purchase_order.js b/erpnext/buying/doctype/purchase_order/purchase_order.js
index fe8642c..ab8ab03 100644
--- a/erpnext/buying/doctype/purchase_order/purchase_order.js
+++ b/erpnext/buying/doctype/purchase_order/purchase_order.js
@@ -21,10 +21,10 @@
 			return erpnext.queries.warehouse(frm.doc);
 		});
 
-		frappe.db.get_value('Buying Settings', {name: 'Buying Settings'}, 'disable_fetch_last_purchase_rate', (r) => {
-			value = r && cint(r.disable_fetch_last_purchase_rate);
-			frm.toggle_display('get_last_purchase_rate', !value);
-		});
+		if (frm.doc.__onload) {
+			frm.toggle_display('get_last_purchase_rate',
+				frm.doc.__onload.disable_fetch_last_purchase_rate);
+		}
 
 		frm.set_indicator_formatter('item_code',
 			function(doc) { return (doc.qty<=doc.received_qty) ? "green" : "orange" })
diff --git a/erpnext/buying/doctype/purchase_order/purchase_order.py b/erpnext/buying/doctype/purchase_order/purchase_order.py
index 1929476..db13bd5 100644
--- a/erpnext/buying/doctype/purchase_order/purchase_order.py
+++ b/erpnext/buying/doctype/purchase_order/purchase_order.py
@@ -34,6 +34,12 @@
 			'overflow_type': 'order'
 		}]
 
+	def onload(self):
+		super(PurchaseOrder, self).onload()
+
+		self.set_onload('disable_fetch_last_purchase_rate',
+			cint(frappe.db.get_single_value("Buying Settings", "disable_fetch_last_purchase_rate")))
+
 	def validate(self):
 		super(PurchaseOrder, self).validate()