diff --git a/erpnext/stock/doctype/packing_slip/packing_slip.py b/erpnext/stock/doctype/packing_slip/packing_slip.py
index b99215c426..4139a19abf 100644
--- a/erpnext/stock/doctype/packing_slip/packing_slip.py
+++ b/erpnext/stock/doctype/packing_slip/packing_slip.py
@@ -49,7 +49,7 @@ class PackingSlip(Document):
 			frappe.msgprint(_("Please specify a valid 'From Case No.'"), raise_exception=1)
 		elif not self.to_case_no:
 			self.to_case_no = self.from_case_no
-		elif self.from_case_no > self.to_case_no:
+		elif cint(self.from_case_no) > cint(self.to_case_no):
 			frappe.msgprint(_("'To Case No.' cannot be less than 'From Case No.'"),
 				raise_exception=1)