diff --git a/erpnext/accounts/doctype/purchase_invoice/purchase_invoice.py b/erpnext/accounts/doctype/purchase_invoice/purchase_invoice.py
index c9a4ff090b4..e0c3f137eeb 100644
--- a/erpnext/accounts/doctype/purchase_invoice/purchase_invoice.py
+++ b/erpnext/accounts/doctype/purchase_invoice/purchase_invoice.py
@@ -410,7 +410,7 @@ def get_expense_account(doctype, txt, searchfield, start, page_len, filters):
 				and tabAccount.docstatus!=2
 				and ifnull(tabAccount.master_type, "")=""
 				and ifnull(tabAccount.master_name, "")=""
-				and tabAccount.company = '%(company)s'
-				and tabAccount.%(key)s LIKE '%(txt)s'
-				%(mcond)s""" % {'company': filters['company'], 'key': searchfield,
-			'txt': "%%%s%%" % txt, 'mcond':get_match_cond(doctype)})
+				and tabAccount.company = %(company)s
+				and tabAccount.{key} LIKE %(txt)s
+				{mcond}""".format(key=searchfield, mcond=get_match_cond(doctype)),
+				{'company': filters['company'], 'txt': "%%{0}%%".format(txt)})
diff --git a/erpnext/accounts/doctype/sales_invoice/sales_invoice.py b/erpnext/accounts/doctype/sales_invoice/sales_invoice.py
index 676a468aa95..8b23115e9a7 100644
--- a/erpnext/accounts/doctype/sales_invoice/sales_invoice.py
+++ b/erpnext/accounts/doctype/sales_invoice/sales_invoice.py
@@ -611,11 +611,10 @@ def get_income_account(doctype, txt, searchfield, start, page_len, filters):
 				and tabAccount.docstatus!=2
 				and ifnull(tabAccount.master_type, "")=""
 				and ifnull(tabAccount.master_name, "")=""
-				and tabAccount.company = '%(company)s'
-				and tabAccount.%(key)s LIKE '%(txt)s'
-				%(mcond)s""" % {'company': filters['company'], 'key': searchfield,
-			'txt': "%%%s%%" % txt, 'mcond':get_match_cond(doctype)})
-
+				and tabAccount.company = %(company)s
+				and tabAccount.{key} LIKE %(txt)s
+				{mcond}""".format(key=searchfield, mcond=get_match_cond(doctype)),
+				{'company': filters['company'], 'txt': "%%{0}%%".format(txt)})
 
 @frappe.whitelist()
 def make_delivery_note(source_name, target_doc=None):
diff --git a/erpnext/selling/report/customers_not_buying_since_long_time/customers_not_buying_since_long_time.py b/erpnext/selling/report/customers_not_buying_since_long_time/customers_not_buying_since_long_time.py
index a87c4a119f8..458ae7bea4a 100644
--- a/erpnext/selling/report/customers_not_buying_since_long_time/customers_not_buying_since_long_time.py
+++ b/erpnext/selling/report/customers_not_buying_since_long_time/customers_not_buying_since_long_time.py
@@ -43,8 +43,8 @@ def get_so_details():
 
 def get_last_so_amt(customer):
 	res =  frappe.db.sql("""select net_total from `tabSales Order`
-		where customer ='%(customer)s' and docstatus = 1 order by transaction_date desc
-		limit 1""" % {'customer':customer})
+		where customer = %(customer)s and docstatus = 1 order by transaction_date desc
+		limit 1""", {'customer':customer})
 
 	return res and res[0][0] or 0