diff --git a/db/migrate/20191203014808_create_subscriptions_customers.rb b/db/migrate/20191203014808_create_subscriptions_customers.rb
index 6254951..c015966 100644
--- a/db/migrate/20191203014808_create_subscriptions_customers.rb
+++ b/db/migrate/20191203014808_create_subscriptions_customers.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class CreateSubscriptionsCustomers < ActiveRecord::Migration[6.0]
   def change
     create_table :discourse_subscriptions_customers do |t|