diff --git a/app/models/bank_transaction.rb b/app/models/bank_transaction.rb
index 76ed9ae27..4b6b6eda0 100644
--- a/app/models/bank_transaction.rb
+++ b/app/models/bank_transaction.rb
@@ -38,11 +38,7 @@ class BankTransaction < ApplicationRecord
     return unless invoice
     return unless invoice.payable?
 
-    channel = if manual
-                'admin_payment'
-              else
-                'system_payment'
-              end
+    channel = manual ? 'admin_payment' : 'system_payment'
     create_internal_payment_record(channel: channel, invoice: invoice,
                                    registrar: registrar)
   end
diff --git a/app/models/billing/reference_no.rb b/app/models/billing/reference_no.rb
index 849c06b85..263100e79 100644
--- a/app/models/billing/reference_no.rb
+++ b/app/models/billing/reference_no.rb
@@ -1,7 +1,7 @@
 module Billing
   class ReferenceNo
-    REGEXP = /\A\d{2,20}\z/
-    MULTI_REGEXP = /(\d{2,20})/
+    REGEXP = /\A\d{2,20}\z/.freeze
+    MULTI_REGEXP = /(\d{2,20})/.freeze
 
     def self.generate
       base = Base.generate