diff --git a/erpnext/crm/doctype/opportunity/opportunity.py b/erpnext/crm/doctype/opportunity/opportunity.py
index 08d413f..0225398 100644
--- a/erpnext/crm/doctype/opportunity/opportunity.py
+++ b/erpnext/crm/doctype/opportunity/opportunity.py
@@ -44,7 +44,7 @@
 
 	def make_new_lead_if_required(self):
 		"""Set lead against new opportunity"""
-		if not self.lead or self.customer:
+		if not (self.lead or self.customer):
 			lead_name = frappe.db.get_value("Lead", {"email_id": self.contact_email})
 			if not lead_name:
 				lead = frappe.get_doc({