diff --git a/frappe/core/doctype/doctype/doctype.py b/frappe/core/doctype/doctype/doctype.py
index 5c558f3bd6..6524036975 100644
--- a/frappe/core/doctype/doctype/doctype.py
+++ b/frappe/core/doctype/doctype/doctype.py
@@ -762,7 +762,7 @@ def validate_fields(meta):
 
 			if not d.get("__islocal") and frappe.db.has_column(d.parent, d.fieldname):
 				has_non_unique_values = frappe.db.sql("""select `{fieldname}`, count(*)
-					from `tab{doctype}` where ifnull({fieldname}, '') != ''
+					from `tab{doctype}` where ifnull(`{fieldname}`, '') != ''
 					group by `{fieldname}` having count(*) > 1 limit 1""".format(
 					doctype=d.parent, fieldname=d.fieldname))