diff --git a/erpnext/setup/doctype/supplier_group/supplier_group.py b/erpnext/setup/doctype/supplier_group/supplier_group.py
index 747560a..fa265d4 100644
--- a/erpnext/setup/doctype/supplier_group/supplier_group.py
+++ b/erpnext/setup/doctype/supplier_group/supplier_group.py
@@ -4,10 +4,13 @@
 
 from __future__ import unicode_literals
 import frappe
-from frappe.utils.nestedset import NestedSet
+from frappe.utils.nestedset import NestedSet, get_root_of
 
 class SupplierGroup(NestedSet):
 	nsm_parent_field = 'parent_supplier_group';
+	def validate(self):
+		if not self.parent_supplier_group:
+			self.parent_supplier_group = get_root_of("Supplier Group")
 
 	def update_nsm_model(self):
 		frappe.utils.nestedset.update_nsm(self)