diff --git a/erpnext/accounts/doctype/pricing_rule/utils.py b/erpnext/accounts/doctype/pricing_rule/utils.py
index c676abd..b91a7a5 100644
--- a/erpnext/accounts/doctype/pricing_rule/utils.py
+++ b/erpnext/accounts/doctype/pricing_rule/utils.py
@@ -471,7 +471,7 @@
 
 					if not d.get(pr_field): continue
 
-					if d.validate_applied_rule and doc.get(field) < d.get(pr_field):
+					if d.validate_applied_rule and doc.get(field) is not None and doc.get(field) < d.get(pr_field):
 						frappe.msgprint(_("User has not applied rule on the invoice {0}")
 							.format(doc.name))
 					else: