diff --git a/app/controllers/controllers.rb b/app/controllers/controllers.rb
index d11f590..46b553e 100644
--- a/app/controllers/controllers.rb
+++ b/app/controllers/controllers.rb
@@ -1,2 +1,4 @@
+# frozen_string_literal: true
+
 load File.expand_path('../discourse_donations/charges_controller.rb', __FILE__)
 load File.expand_path('../discourse_donations/checkout_controller.rb', __FILE__)
diff --git a/app/controllers/discourse_donations/charges_controller.rb b/app/controllers/discourse_donations/charges_controller.rb
index 6835543..d182ce0 100644
--- a/app/controllers/discourse_donations/charges_controller.rb
+++ b/app/controllers/discourse_donations/charges_controller.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module DiscourseDonations
   class ChargesController < ::ApplicationController
     skip_before_action :verify_authenticity_token, only: [:create]
diff --git a/app/controllers/discourse_donations/checkout_controller.rb b/app/controllers/discourse_donations/checkout_controller.rb
index 946729c..24206e1 100644
--- a/app/controllers/discourse_donations/checkout_controller.rb
+++ b/app/controllers/discourse_donations/checkout_controller.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require_dependency 'discourse'
 
 module DiscourseDonations
diff --git a/app/jobs/jobs.rb b/app/jobs/jobs.rb
index 1a1620c..5c38931 100644
--- a/app/jobs/jobs.rb
+++ b/app/jobs/jobs.rb
@@ -1,2 +1,4 @@
+# frozen_string_literal: true
+
 load File.expand_path('../regular/donation_user.rb', __FILE__)
 load File.expand_path('../scheduled/update_category_donation_statistics.rb', __FILE__)
diff --git a/app/jobs/regular/donation_user.rb b/app/jobs/regular/donation_user.rb
index 5f28c78..88ea75d 100644
--- a/app/jobs/regular/donation_user.rb
+++ b/app/jobs/regular/donation_user.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 
 module Jobs
   class DonationUser < ::Jobs::Base
diff --git a/app/jobs/scheduled/update_category_donation_statistics.rb b/app/jobs/scheduled/update_category_donation_statistics.rb
index 0d338a8..5046656 100644
--- a/app/jobs/scheduled/update_category_donation_statistics.rb
+++ b/app/jobs/scheduled/update_category_donation_statistics.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Jobs
   class UpdateCategoryDonationStatistics < ::Jobs::Scheduled
     every 1.day
diff --git a/app/services/discourse_donations/rewards.rb b/app/services/discourse_donations/rewards.rb
index 7b2dca1..93596c4 100644
--- a/app/services/discourse_donations/rewards.rb
+++ b/app/services/discourse_donations/rewards.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 
 module DiscourseDonations
   class Rewards
diff --git a/app/services/discourse_donations/stripe.rb b/app/services/discourse_donations/stripe.rb
index a988d25..199d59e 100644
--- a/app/services/discourse_donations/stripe.rb
+++ b/app/services/discourse_donations/stripe.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module DiscourseDonations
   class Stripe
     attr_reader :charge, :currency, :description
diff --git a/app/services/services.rb b/app/services/services.rb
index 8e8aabc..73924a0 100644
--- a/app/services/services.rb
+++ b/app/services/services.rb
@@ -1,2 +1,4 @@
+# frozen_string_literal: true
+
 load File.expand_path('../discourse_donations/rewards.rb', __FILE__)
 load File.expand_path('../discourse_donations/stripe.rb', __FILE__)
diff --git a/config/routes.rb b/config/routes.rb
index b08fab8..5314102 100644
--- a/config/routes.rb
+++ b/config/routes.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 DiscourseDonations::Engine.routes.draw do
   get '/' => 'charges#index'
 
diff --git a/lib/discourse_donations/engine.rb b/lib/discourse_donations/engine.rb
index d92e065..41a41c5 100644
--- a/lib/discourse_donations/engine.rb
+++ b/lib/discourse_donations/engine.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module ::DiscourseDonations
   class Engine < ::Rails::Engine
     engine_name 'discourse-donations'
diff --git a/plugin.rb b/plugin.rb
index c24ba1b..f03ce5f 100644
--- a/plugin.rb
+++ b/plugin.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # name: discourse-donations
 # about: Integrates Stripe into Discourse to allow forum visitors to make donations
 # version: 1.11.3
diff --git a/spec/controllers/discourse_donations/charges_controller_spec.rb b/spec/controllers/discourse_donations/charges_controller_spec.rb
index a0342e1..edd70f8 100644
--- a/spec/controllers/discourse_donations/charges_controller_spec.rb
+++ b/spec/controllers/discourse_donations/charges_controller_spec.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'rails_helper'
 
 shared_examples 'failure response' do |message_key|
diff --git a/spec/fabricators/charge_fabricator.rb b/spec/fabricators/charge_fabricator.rb
index e45e8eb..9a08a61 100644
--- a/spec/fabricators/charge_fabricator.rb
+++ b/spec/fabricators/charge_fabricator.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 
 Fabricator(:stripe_charge, from: "DiscourseDonations::StripeResponse") do
   response = {
diff --git a/spec/fabricators/customer_fabricator.rb b/spec/fabricators/customer_fabricator.rb
index e306e69..6222092 100644
--- a/spec/fabricators/customer_fabricator.rb
+++ b/spec/fabricators/customer_fabricator.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 
 Fabricator(:stripe_customer, from: "DiscourseDonations::StripeResponse") do
   response = {
diff --git a/spec/fabricators/invoices_fabricator.rb b/spec/fabricators/invoices_fabricator.rb
index 6d8630e..d4c823c 100644
--- a/spec/fabricators/invoices_fabricator.rb
+++ b/spec/fabricators/invoices_fabricator.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 
 Fabricator(:stripe_invoices, from: "DiscourseDonations::StripeResponse") do
   response = {
diff --git a/spec/fabricators/plans_fabricator.rb b/spec/fabricators/plans_fabricator.rb
index a88f19a..cd4effd 100644
--- a/spec/fabricators/plans_fabricator.rb
+++ b/spec/fabricators/plans_fabricator.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 
 Fabricator(:stripe_plans, from: "DiscourseDonations::StripeResponse") do
   response = {
diff --git a/spec/fabricators/products_fabricator.rb b/spec/fabricators/products_fabricator.rb
index 6da49a4..ff9cbcf 100644
--- a/spec/fabricators/products_fabricator.rb
+++ b/spec/fabricators/products_fabricator.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 
 Fabricator(:stripe_products, from: "DiscourseDonations::StripeResponse") do
   response = {
diff --git a/spec/fabricators/stripe_response.rb b/spec/fabricators/stripe_response.rb
index 5e68f95..6649fad 100644
--- a/spec/fabricators/stripe_response.rb
+++ b/spec/fabricators/stripe_response.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 
 # This is for building http responses with Fabricate
 # Usage: Fabricate(:customer).to_json
diff --git a/spec/fabricators/subscription_fabricator.rb b/spec/fabricators/subscription_fabricator.rb
index c6d76b8..75a716d 100644
--- a/spec/fabricators/subscription_fabricator.rb
+++ b/spec/fabricators/subscription_fabricator.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 
 Fabricator(:stripe_subscription, from: "DiscourseDonations::StripeResponse") do
   response = {
diff --git a/spec/jobs/regular/donation_user_spec.rb b/spec/jobs/regular/donation_user_spec.rb
index cdaef35..fa09fea 100644
--- a/spec/jobs/regular/donation_user_spec.rb
+++ b/spec/jobs/regular/donation_user_spec.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'rails_helper'
 
 RSpec.describe Jobs::DonationUser, type: :job do
diff --git a/spec/plugin_helper.rb b/spec/plugin_helper.rb
index ecab67d..aa3fb30 100644
--- a/spec/plugin_helper.rb
+++ b/spec/plugin_helper.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 
 require_relative './fabricators/charge_fabricator.rb'
 require_relative './fabricators/customer_fabricator.rb'
diff --git a/spec/services/discourse_donations/rewards_spec.rb b/spec/services/discourse_donations/rewards_spec.rb
index f2ce760..f39956b 100644
--- a/spec/services/discourse_donations/rewards_spec.rb
+++ b/spec/services/discourse_donations/rewards_spec.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'rails_helper'
 
 module DiscourseDonations
diff --git a/spec/services/discourse_donations/stripe_spec.rb b/spec/services/discourse_donations/stripe_spec.rb
index 5cc1b36..f49e1fe 100644
--- a/spec/services/discourse_donations/stripe_spec.rb
+++ b/spec/services/discourse_donations/stripe_spec.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'rails_helper'
 require_relative '../../support/dd_helper'
 
@@ -61,7 +63,7 @@ module DiscourseDonations
           description: stripe_options[:description],
           currency: stripe_options[:currency],
           receipt_email: customer.email,
-          :metadata => { :discourse_cause => nil }
+          metadata: { discourse_cause: nil }
         }
       end
 
@@ -72,7 +74,7 @@ module DiscourseDonations
       it 'is successful' do
         ::Stripe::Charge.expects(:create).with(charge_options).returns(paid: true)
 
-        ::Stripe::Customer.expects(:list).returns({ data: [] })
+        ::Stripe::Customer.expects(:list).returns(data: [])
 
         subject.charge(nil, params)
         expect(subject).to be_successful
@@ -80,7 +82,7 @@ module DiscourseDonations
 
       it 'is not successful' do
         ::Stripe::Charge.expects(:create).with(charge_options).returns(paid: false)
-        ::Stripe::Customer.expects(:list).returns({ data: [] })
+        ::Stripe::Customer.expects(:list).returns(data: [])
         subject.charge(nil, params)
         expect(subject).not_to be_successful
       end
diff --git a/spec/support/dd_helper.rb b/spec/support/dd_helper.rb
index 3c196f0..051d6fb 100644
--- a/spec/support/dd_helper.rb
+++ b/spec/support/dd_helper.rb
@@ -1,9 +1,11 @@
+# frozen_string_literal: true
+
 require 'fakeweb'
 
 #TODO register some fixtures
 
 FakeWeb.register_uri(:post, 'https://api.stripe.com/v1/customers',
-  :body => '{
+  body: '{
   "id": "cus_AJqrL4OU1sffPl",
   "object": "customer",
   "account_balance": 0,
@@ -52,11 +54,11 @@ FakeWeb.register_uri(:post, 'https://api.stripe.com/v1/customers',
   "url": "/v1/customers/cus_AJqrL4OU1sffPl/sources"
   }
   }',
-  :status => ['200', 'OK']
+  status: ['200', 'OK']
 )
 
 FakeWeb.register_uri(:post, 'https://api.stripe.com/v1/charges',
-  :body => '{
+  body: '{
   "id": "ch_19zDAFEfVxQsvRbHtAwsCvV0",
   "object": "charge",
   "amount": 100,
@@ -133,5 +135,5 @@ FakeWeb.register_uri(:post, 'https://api.stripe.com/v1/charges',
   "status": "succeeded",
   "transfer_group": null
   }',
-  :status => ['200', 'OK']
+  status: ['200', 'OK']
 )