diff --git a/.rubocop.yml b/.rubocop.yml
index 8c0f48a7f..031686797 100644
--- a/.rubocop.yml
+++ b/.rubocop.yml
@@ -13,6 +13,9 @@ Layout/IndentArray:
 Layout/IndentHash:
   EnforcedStyle: consistent
 
+Style/FrozenStringLiteralComment:
+  EnforcedStyle: always
+
 Style/StringLiterals:
   EnforcedStyle: double_quotes
 
diff --git a/Gemfile b/Gemfile
index 808b57053..8d13dd037 100644
--- a/Gemfile
+++ b/Gemfile
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 source "https://rubygems.org"
 
 gemspec
diff --git a/Rakefile b/Rakefile
index 495981330..0284c1389 100644
--- a/Rakefile
+++ b/Rakefile
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require "rake/testtask"
 require "rubocop/rake_task"
 
diff --git a/bin/stripe-console b/bin/stripe-console
index e7b1cce7e..ecf27d2f2 100755
--- a/bin/stripe-console
+++ b/bin/stripe-console
@@ -1,5 +1,7 @@
 #!/usr/bin/env ruby
 
+# frozen_string_literal: true
+
 require "irb"
 require "irb/completion"
 
diff --git a/lib/stripe.rb b/lib/stripe.rb
index ac70d20ca..e5732d19f 100644
--- a/lib/stripe.rb
+++ b/lib/stripe.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # Stripe Ruby bindings
 # API spec at https://stripe.com/docs/api
 require "cgi"
diff --git a/lib/stripe/account.rb b/lib/stripe/account.rb
index 966261bf5..000a06100 100644
--- a/lib/stripe/account.rb
+++ b/lib/stripe/account.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   class Account < APIResource
     extend Gem::Deprecate
diff --git a/lib/stripe/alipay_account.rb b/lib/stripe/alipay_account.rb
index e0e1ee870..ea92b5692 100644
--- a/lib/stripe/alipay_account.rb
+++ b/lib/stripe/alipay_account.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   class AlipayAccount < APIResource
     include Stripe::APIOperations::Save
diff --git a/lib/stripe/api_operations/create.rb b/lib/stripe/api_operations/create.rb
index 1ec29873b..831859e2e 100644
--- a/lib/stripe/api_operations/create.rb
+++ b/lib/stripe/api_operations/create.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   module APIOperations
     module Create
diff --git a/lib/stripe/api_operations/delete.rb b/lib/stripe/api_operations/delete.rb
index aa047bae2..35571cf19 100644
--- a/lib/stripe/api_operations/delete.rb
+++ b/lib/stripe/api_operations/delete.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   module APIOperations
     module Delete
diff --git a/lib/stripe/api_operations/list.rb b/lib/stripe/api_operations/list.rb
index 4c46930e6..65c46adc0 100644
--- a/lib/stripe/api_operations/list.rb
+++ b/lib/stripe/api_operations/list.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   module APIOperations
     module List
diff --git a/lib/stripe/api_operations/nested_resource.rb b/lib/stripe/api_operations/nested_resource.rb
index 36deff3a2..bee575b17 100644
--- a/lib/stripe/api_operations/nested_resource.rb
+++ b/lib/stripe/api_operations/nested_resource.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   module APIOperations
     # Adds methods to help manipulate a subresource from its parent resource so
diff --git a/lib/stripe/api_operations/request.rb b/lib/stripe/api_operations/request.rb
index 70a6ecc05..cf38b482b 100644
--- a/lib/stripe/api_operations/request.rb
+++ b/lib/stripe/api_operations/request.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   module APIOperations
     module Request
diff --git a/lib/stripe/api_operations/save.rb b/lib/stripe/api_operations/save.rb
index 77add5cdd..566becbb4 100644
--- a/lib/stripe/api_operations/save.rb
+++ b/lib/stripe/api_operations/save.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   module APIOperations
     module Save
diff --git a/lib/stripe/api_resource.rb b/lib/stripe/api_resource.rb
index 75b25c4ed..d31d0c463 100644
--- a/lib/stripe/api_resource.rb
+++ b/lib/stripe/api_resource.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   class APIResource < StripeObject
     include Stripe::APIOperations::Request
diff --git a/lib/stripe/apple_pay_domain.rb b/lib/stripe/apple_pay_domain.rb
index 21fa53fdf..740f1f10d 100644
--- a/lib/stripe/apple_pay_domain.rb
+++ b/lib/stripe/apple_pay_domain.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   # Domains registered for Apple Pay on the Web
   class ApplePayDomain < APIResource
diff --git a/lib/stripe/application_fee.rb b/lib/stripe/application_fee.rb
index 375f08520..0691a70a4 100644
--- a/lib/stripe/application_fee.rb
+++ b/lib/stripe/application_fee.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   class ApplicationFee < APIResource
     extend Stripe::APIOperations::List
diff --git a/lib/stripe/application_fee_refund.rb b/lib/stripe/application_fee_refund.rb
index 1b29a75ea..27fded1cc 100644
--- a/lib/stripe/application_fee_refund.rb
+++ b/lib/stripe/application_fee_refund.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   class ApplicationFeeRefund < APIResource
     include Stripe::APIOperations::Save
diff --git a/lib/stripe/balance.rb b/lib/stripe/balance.rb
index bd1fc6d57..34b9d64e2 100644
--- a/lib/stripe/balance.rb
+++ b/lib/stripe/balance.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   class Balance < SingletonAPIResource
     OBJECT_NAME = "balance".freeze
diff --git a/lib/stripe/balance_transaction.rb b/lib/stripe/balance_transaction.rb
index 0232c3386..2bc646760 100644
--- a/lib/stripe/balance_transaction.rb
+++ b/lib/stripe/balance_transaction.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   class BalanceTransaction < APIResource
     extend Stripe::APIOperations::List
diff --git a/lib/stripe/bank_account.rb b/lib/stripe/bank_account.rb
index a57ba5b14..53d0688a7 100644
--- a/lib/stripe/bank_account.rb
+++ b/lib/stripe/bank_account.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   class BankAccount < APIResource
     include Stripe::APIOperations::Save
diff --git a/lib/stripe/bitcoin_receiver.rb b/lib/stripe/bitcoin_receiver.rb
index b5091f1b8..f9f960f31 100644
--- a/lib/stripe/bitcoin_receiver.rb
+++ b/lib/stripe/bitcoin_receiver.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   class BitcoinReceiver < APIResource
     # Directly creating or retrieving BitcoinReceivers is deprecated. Please use
diff --git a/lib/stripe/bitcoin_transaction.rb b/lib/stripe/bitcoin_transaction.rb
index 941a30560..966937cb0 100644
--- a/lib/stripe/bitcoin_transaction.rb
+++ b/lib/stripe/bitcoin_transaction.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   class BitcoinTransaction < APIResource
     # Directly retrieving BitcoinTransactions is deprecated. Please use the
diff --git a/lib/stripe/card.rb b/lib/stripe/card.rb
index 523e9f5eb..0bd1dc32d 100644
--- a/lib/stripe/card.rb
+++ b/lib/stripe/card.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   class Card < APIResource
     include Stripe::APIOperations::Save
diff --git a/lib/stripe/charge.rb b/lib/stripe/charge.rb
index eff0a6c65..96ce19d94 100644
--- a/lib/stripe/charge.rb
+++ b/lib/stripe/charge.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   class Charge < APIResource
     extend Stripe::APIOperations::List
diff --git a/lib/stripe/country_spec.rb b/lib/stripe/country_spec.rb
index 06bdc2f60..4bae8ffd4 100644
--- a/lib/stripe/country_spec.rb
+++ b/lib/stripe/country_spec.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   class CountrySpec < APIResource
     extend Stripe::APIOperations::List
diff --git a/lib/stripe/coupon.rb b/lib/stripe/coupon.rb
index 5439abe51..767500e32 100644
--- a/lib/stripe/coupon.rb
+++ b/lib/stripe/coupon.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   class Coupon < APIResource
     extend Stripe::APIOperations::Create
diff --git a/lib/stripe/customer.rb b/lib/stripe/customer.rb
index 21bce5bae..c37033901 100644
--- a/lib/stripe/customer.rb
+++ b/lib/stripe/customer.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   class Customer < APIResource
     extend Stripe::APIOperations::Create
diff --git a/lib/stripe/dispute.rb b/lib/stripe/dispute.rb
index abfbd1ae3..5b7f2892f 100644
--- a/lib/stripe/dispute.rb
+++ b/lib/stripe/dispute.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   class Dispute < APIResource
     extend Stripe::APIOperations::List
diff --git a/lib/stripe/ephemeral_key.rb b/lib/stripe/ephemeral_key.rb
index 16431f760..96c18493c 100644
--- a/lib/stripe/ephemeral_key.rb
+++ b/lib/stripe/ephemeral_key.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   class EphemeralKey < APIResource
     extend Stripe::APIOperations::Create
diff --git a/lib/stripe/errors.rb b/lib/stripe/errors.rb
index c4af5a7a1..b5c2032ca 100644
--- a/lib/stripe/errors.rb
+++ b/lib/stripe/errors.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   # StripeError is the base error from which all other more specific Stripe
   # errors derive.
diff --git a/lib/stripe/event.rb b/lib/stripe/event.rb
index 18fe68fd5..5a627a523 100644
--- a/lib/stripe/event.rb
+++ b/lib/stripe/event.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   class Event < APIResource
     extend Stripe::APIOperations::List
diff --git a/lib/stripe/exchange_rate.rb b/lib/stripe/exchange_rate.rb
index ccebbbbfa..2db05dfac 100644
--- a/lib/stripe/exchange_rate.rb
+++ b/lib/stripe/exchange_rate.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   class ExchangeRate < APIResource
     extend Stripe::APIOperations::List
diff --git a/lib/stripe/file_upload.rb b/lib/stripe/file_upload.rb
index 983548a40..f598ab012 100644
--- a/lib/stripe/file_upload.rb
+++ b/lib/stripe/file_upload.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   class FileUpload < APIResource
     extend Stripe::APIOperations::Create
diff --git a/lib/stripe/invoice.rb b/lib/stripe/invoice.rb
index bc84d3592..495d66691 100644
--- a/lib/stripe/invoice.rb
+++ b/lib/stripe/invoice.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   class Invoice < APIResource
     extend Stripe::APIOperations::List
diff --git a/lib/stripe/invoice_item.rb b/lib/stripe/invoice_item.rb
index 12f6373a8..e5d9b6268 100644
--- a/lib/stripe/invoice_item.rb
+++ b/lib/stripe/invoice_item.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   class InvoiceItem < APIResource
     extend Stripe::APIOperations::List
diff --git a/lib/stripe/invoice_line_item.rb b/lib/stripe/invoice_line_item.rb
index 4703d7fcb..a2056bbc4 100644
--- a/lib/stripe/invoice_line_item.rb
+++ b/lib/stripe/invoice_line_item.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   class InvoiceLineItem < StripeObject
     OBJECT_NAME = "line_item".freeze
diff --git a/lib/stripe/issuer_fraud_record.rb b/lib/stripe/issuer_fraud_record.rb
index c686ae590..835b5a8c1 100644
--- a/lib/stripe/issuer_fraud_record.rb
+++ b/lib/stripe/issuer_fraud_record.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   class IssuerFraudRecord < APIResource
     extend Stripe::APIOperations::List
diff --git a/lib/stripe/list_object.rb b/lib/stripe/list_object.rb
index 343d141ee..58cae0adb 100644
--- a/lib/stripe/list_object.rb
+++ b/lib/stripe/list_object.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   class ListObject < StripeObject
     include Enumerable
diff --git a/lib/stripe/login_link.rb b/lib/stripe/login_link.rb
index f2b41e4c2..09eba2f4b 100644
--- a/lib/stripe/login_link.rb
+++ b/lib/stripe/login_link.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   class LoginLink < APIResource
     OBJECT_NAME = "login_link".freeze
diff --git a/lib/stripe/oauth.rb b/lib/stripe/oauth.rb
index d1b55efa1..a07778ae6 100644
--- a/lib/stripe/oauth.rb
+++ b/lib/stripe/oauth.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   module OAuth
     module OAuthOperations
diff --git a/lib/stripe/order.rb b/lib/stripe/order.rb
index c0d682314..3ad042de1 100644
--- a/lib/stripe/order.rb
+++ b/lib/stripe/order.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   class Order < APIResource
     extend Stripe::APIOperations::List
diff --git a/lib/stripe/order_return.rb b/lib/stripe/order_return.rb
index ee0683a7a..6940a6f57 100644
--- a/lib/stripe/order_return.rb
+++ b/lib/stripe/order_return.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   class OrderReturn < APIResource
     extend Stripe::APIOperations::List
diff --git a/lib/stripe/payout.rb b/lib/stripe/payout.rb
index 91893a5df..335da40e2 100644
--- a/lib/stripe/payout.rb
+++ b/lib/stripe/payout.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   class Payout < APIResource
     extend Stripe::APIOperations::List
diff --git a/lib/stripe/plan.rb b/lib/stripe/plan.rb
index fe01be2be..192bf301b 100644
--- a/lib/stripe/plan.rb
+++ b/lib/stripe/plan.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   class Plan < APIResource
     extend Stripe::APIOperations::Create
diff --git a/lib/stripe/product.rb b/lib/stripe/product.rb
index f7fe6c5b5..56466908e 100644
--- a/lib/stripe/product.rb
+++ b/lib/stripe/product.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   class Product < APIResource
     extend Stripe::APIOperations::List
diff --git a/lib/stripe/recipient.rb b/lib/stripe/recipient.rb
index da20d07a6..bd2d603e8 100644
--- a/lib/stripe/recipient.rb
+++ b/lib/stripe/recipient.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   # Recipients objects are deprecated. Please use Stripe Connect instead.
   class Recipient < APIResource
diff --git a/lib/stripe/recipient_transfer.rb b/lib/stripe/recipient_transfer.rb
index 7128a689d..30faaaee3 100644
--- a/lib/stripe/recipient_transfer.rb
+++ b/lib/stripe/recipient_transfer.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   class RecipientTransfer < StripeObject
     OBJECT_NAME = "recipient_transfer".freeze
diff --git a/lib/stripe/refund.rb b/lib/stripe/refund.rb
index c08330103..b832b0f07 100644
--- a/lib/stripe/refund.rb
+++ b/lib/stripe/refund.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   class Refund < APIResource
     extend Stripe::APIOperations::Create
diff --git a/lib/stripe/reversal.rb b/lib/stripe/reversal.rb
index 42d9de732..725de0672 100644
--- a/lib/stripe/reversal.rb
+++ b/lib/stripe/reversal.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   class Reversal < APIResource
     extend Stripe::APIOperations::List
diff --git a/lib/stripe/singleton_api_resource.rb b/lib/stripe/singleton_api_resource.rb
index 2748647d5..00abb51ff 100644
--- a/lib/stripe/singleton_api_resource.rb
+++ b/lib/stripe/singleton_api_resource.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   class SingletonAPIResource < APIResource
     def self.resource_url
diff --git a/lib/stripe/sku.rb b/lib/stripe/sku.rb
index ada998bb9..c60e70984 100644
--- a/lib/stripe/sku.rb
+++ b/lib/stripe/sku.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   class SKU < APIResource
     extend Stripe::APIOperations::List
diff --git a/lib/stripe/source.rb b/lib/stripe/source.rb
index 399eaba3b..cfa60715a 100644
--- a/lib/stripe/source.rb
+++ b/lib/stripe/source.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   class Source < APIResource
     extend Stripe::APIOperations::Create
diff --git a/lib/stripe/source_transaction.rb b/lib/stripe/source_transaction.rb
index a661a9a51..545162a03 100644
--- a/lib/stripe/source_transaction.rb
+++ b/lib/stripe/source_transaction.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   class SourceTransaction < StripeObject
     OBJECT_NAME = "source_transaction".freeze
diff --git a/lib/stripe/stripe_client.rb b/lib/stripe/stripe_client.rb
index c98a47687..523f4873d 100644
--- a/lib/stripe/stripe_client.rb
+++ b/lib/stripe/stripe_client.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   # StripeClient executes requests against the Stripe API and allows a user to
   # recover both a resource a call returns as well as a response object that
diff --git a/lib/stripe/stripe_object.rb b/lib/stripe/stripe_object.rb
index 3aca0757e..de92a4568 100644
--- a/lib/stripe/stripe_object.rb
+++ b/lib/stripe/stripe_object.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   class StripeObject
     include Enumerable
diff --git a/lib/stripe/stripe_response.rb b/lib/stripe/stripe_response.rb
index 3bae162f9..2028d1cc7 100644
--- a/lib/stripe/stripe_response.rb
+++ b/lib/stripe/stripe_response.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   # StripeResponse encapsulates some vitals of a response that came back from
   # the Stripe API.
diff --git a/lib/stripe/subscription.rb b/lib/stripe/subscription.rb
index 90ec34429..285953dac 100644
--- a/lib/stripe/subscription.rb
+++ b/lib/stripe/subscription.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   class Subscription < APIResource
     extend Stripe::APIOperations::List
diff --git a/lib/stripe/subscription_item.rb b/lib/stripe/subscription_item.rb
index ab3da8360..91689feb1 100644
--- a/lib/stripe/subscription_item.rb
+++ b/lib/stripe/subscription_item.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   class SubscriptionItem < APIResource
     extend Stripe::APIOperations::Create
diff --git a/lib/stripe/three_d_secure.rb b/lib/stripe/three_d_secure.rb
index 191056f4e..e713eb0a9 100644
--- a/lib/stripe/three_d_secure.rb
+++ b/lib/stripe/three_d_secure.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   class ThreeDSecure < APIResource
     extend Stripe::APIOperations::Create
diff --git a/lib/stripe/token.rb b/lib/stripe/token.rb
index 71ed05249..acf35275c 100644
--- a/lib/stripe/token.rb
+++ b/lib/stripe/token.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   class Token < APIResource
     extend Stripe::APIOperations::Create
diff --git a/lib/stripe/topup.rb b/lib/stripe/topup.rb
index 619310fd1..21218e71a 100644
--- a/lib/stripe/topup.rb
+++ b/lib/stripe/topup.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   class Topup < APIResource
     extend Stripe::APIOperations::List
diff --git a/lib/stripe/transfer.rb b/lib/stripe/transfer.rb
index a8d5bbaaf..a96e89cae 100644
--- a/lib/stripe/transfer.rb
+++ b/lib/stripe/transfer.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   class Transfer < APIResource
     extend Stripe::APIOperations::List
diff --git a/lib/stripe/usage_record.rb b/lib/stripe/usage_record.rb
index 255001d54..9f18788ed 100644
--- a/lib/stripe/usage_record.rb
+++ b/lib/stripe/usage_record.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   class UsageRecord < APIResource
     def self.create(params = {}, opts = {})
diff --git a/lib/stripe/util.rb b/lib/stripe/util.rb
index c2a4691d2..ebdfa23a2 100644
--- a/lib/stripe/util.rb
+++ b/lib/stripe/util.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require "cgi"
 
 module Stripe
diff --git a/lib/stripe/version.rb b/lib/stripe/version.rb
index 91b27e6f4..24f9e11ac 100644
--- a/lib/stripe/version.rb
+++ b/lib/stripe/version.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   VERSION = "3.14.0".freeze
 end
diff --git a/lib/stripe/webhook.rb b/lib/stripe/webhook.rb
index 0e00890f0..ae8615b4c 100644
--- a/lib/stripe/webhook.rb
+++ b/lib/stripe/webhook.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   module Webhook
     DEFAULT_TOLERANCE = 300
diff --git a/stripe.gemspec b/stripe.gemspec
index ad18963d7..e77dcad2e 100644
--- a/stripe.gemspec
+++ b/stripe.gemspec
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 $LOAD_PATH.unshift(File.join(File.dirname(__FILE__), "lib"))
 
 require "stripe/version"
diff --git a/test/api_stub_helpers.rb b/test/api_stub_helpers.rb
index e69de29bb..8e9b8f90f 100644
--- a/test/api_stub_helpers.rb
+++ b/test/api_stub_helpers.rb
@@ -0,0 +1 @@
+# frozen_string_literal: true
diff --git a/test/stripe/account_external_accounts_operations_test.rb b/test/stripe/account_external_accounts_operations_test.rb
index 94ff50e00..703ef6a50 100644
--- a/test/stripe/account_external_accounts_operations_test.rb
+++ b/test/stripe/account_external_accounts_operations_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require File.expand_path("../../test_helper", __FILE__)
 
 module Stripe
diff --git a/test/stripe/account_login_links_operations_test.rb b/test/stripe/account_login_links_operations_test.rb
index a2e3f7409..3671ce3dd 100644
--- a/test/stripe/account_login_links_operations_test.rb
+++ b/test/stripe/account_login_links_operations_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require File.expand_path("../../test_helper", __FILE__)
 
 module Stripe
diff --git a/test/stripe/account_test.rb b/test/stripe/account_test.rb
index 198bc68f8..2cbc7980d 100644
--- a/test/stripe/account_test.rb
+++ b/test/stripe/account_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require File.expand_path("../../test_helper", __FILE__)
 
 module Stripe
diff --git a/test/stripe/alipay_account_test.rb b/test/stripe/alipay_account_test.rb
index f59253f27..e960f1cf4 100644
--- a/test/stripe/alipay_account_test.rb
+++ b/test/stripe/alipay_account_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require File.expand_path("../../test_helper", __FILE__)
 
 module Stripe
diff --git a/test/stripe/api_operations_test.rb b/test/stripe/api_operations_test.rb
index 4412d1df4..962eaaea3 100644
--- a/test/stripe/api_operations_test.rb
+++ b/test/stripe/api_operations_test.rb
@@ -1,4 +1,6 @@
 # -*- coding: utf-8 -*-
+# frozen_string_literal: true
+
 require File.expand_path("../../test_helper", __FILE__)
 
 module Stripe
diff --git a/test/stripe/api_resource_test.rb b/test/stripe/api_resource_test.rb
index 336b31c5f..f160fe86d 100644
--- a/test/stripe/api_resource_test.rb
+++ b/test/stripe/api_resource_test.rb
@@ -1,4 +1,6 @@
 # -*- coding: utf-8 -*-
+# frozen_string_literal: true
+
 require File.expand_path("../../test_helper", __FILE__)
 
 module Stripe
diff --git a/test/stripe/apple_pay_domain_test.rb b/test/stripe/apple_pay_domain_test.rb
index 5c792dca6..3ac50d9fb 100644
--- a/test/stripe/apple_pay_domain_test.rb
+++ b/test/stripe/apple_pay_domain_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require File.expand_path("../../test_helper", __FILE__)
 
 module Stripe
diff --git a/test/stripe/application_fee_refund_test.rb b/test/stripe/application_fee_refund_test.rb
index 07d7c5e7c..c63d7834e 100644
--- a/test/stripe/application_fee_refund_test.rb
+++ b/test/stripe/application_fee_refund_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require File.expand_path("../../test_helper", __FILE__)
 
 module Stripe
diff --git a/test/stripe/application_fee_refunds_operations_test.rb b/test/stripe/application_fee_refunds_operations_test.rb
index 223c3cac7..2f4ad683e 100644
--- a/test/stripe/application_fee_refunds_operations_test.rb
+++ b/test/stripe/application_fee_refunds_operations_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require File.expand_path("../../test_helper", __FILE__)
 
 module Stripe
diff --git a/test/stripe/application_fee_test.rb b/test/stripe/application_fee_test.rb
index bed487876..0cabb9b0c 100644
--- a/test/stripe/application_fee_test.rb
+++ b/test/stripe/application_fee_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require File.expand_path("../../test_helper", __FILE__)
 
 module Stripe
diff --git a/test/stripe/balance_test.rb b/test/stripe/balance_test.rb
index 22a707204..772508b54 100644
--- a/test/stripe/balance_test.rb
+++ b/test/stripe/balance_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require File.expand_path("../../test_helper", __FILE__)
 
 module Stripe
diff --git a/test/stripe/bank_account_test.rb b/test/stripe/bank_account_test.rb
index 7ddc201c2..f0ebc0655 100644
--- a/test/stripe/bank_account_test.rb
+++ b/test/stripe/bank_account_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require File.expand_path("../../test_helper", __FILE__)
 
 module Stripe
diff --git a/test/stripe/charge_test.rb b/test/stripe/charge_test.rb
index dadc3530d..44b0da7ce 100644
--- a/test/stripe/charge_test.rb
+++ b/test/stripe/charge_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require File.expand_path("../../test_helper", __FILE__)
 
 module Stripe
diff --git a/test/stripe/country_spec_test.rb b/test/stripe/country_spec_test.rb
index 2dc9e5632..c1e69b787 100644
--- a/test/stripe/country_spec_test.rb
+++ b/test/stripe/country_spec_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require File.expand_path("../../test_helper", __FILE__)
 
 module Stripe
diff --git a/test/stripe/coupon_test.rb b/test/stripe/coupon_test.rb
index bc8e491c2..848be4498 100644
--- a/test/stripe/coupon_test.rb
+++ b/test/stripe/coupon_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require File.expand_path("../../test_helper", __FILE__)
 
 module Stripe
diff --git a/test/stripe/customer_card_test.rb b/test/stripe/customer_card_test.rb
index ab844a146..3e6658fc8 100644
--- a/test/stripe/customer_card_test.rb
+++ b/test/stripe/customer_card_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require File.expand_path("../../test_helper", __FILE__)
 
 module Stripe
diff --git a/test/stripe/customer_sources_operations_test.rb b/test/stripe/customer_sources_operations_test.rb
index c86abcc1f..b89b688e5 100644
--- a/test/stripe/customer_sources_operations_test.rb
+++ b/test/stripe/customer_sources_operations_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require File.expand_path("../../test_helper", __FILE__)
 
 module Stripe
diff --git a/test/stripe/customer_test.rb b/test/stripe/customer_test.rb
index ae94b4f3d..d119d1563 100644
--- a/test/stripe/customer_test.rb
+++ b/test/stripe/customer_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require File.expand_path("../../test_helper", __FILE__)
 
 module Stripe
diff --git a/test/stripe/dispute_test.rb b/test/stripe/dispute_test.rb
index 373a4f3f5..8539140e6 100644
--- a/test/stripe/dispute_test.rb
+++ b/test/stripe/dispute_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require File.expand_path("../../test_helper", __FILE__)
 
 module Stripe
diff --git a/test/stripe/ephemeral_key_test.rb b/test/stripe/ephemeral_key_test.rb
index f03409ff3..90dd4f861 100644
--- a/test/stripe/ephemeral_key_test.rb
+++ b/test/stripe/ephemeral_key_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require File.expand_path("../../test_helper", __FILE__)
 
 module Stripe
diff --git a/test/stripe/errors_test.rb b/test/stripe/errors_test.rb
index 4f8a1fe59..9f94e0a87 100644
--- a/test/stripe/errors_test.rb
+++ b/test/stripe/errors_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require File.expand_path("../../test_helper", __FILE__)
 
 module Stripe
diff --git a/test/stripe/exchange_rate_test.rb b/test/stripe/exchange_rate_test.rb
index 65a2ff678..8156eb779 100644
--- a/test/stripe/exchange_rate_test.rb
+++ b/test/stripe/exchange_rate_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require File.expand_path("../../test_helper", __FILE__)
 
 module Stripe
diff --git a/test/stripe/file_upload_test.rb b/test/stripe/file_upload_test.rb
index b2448fcf2..fa79a09d5 100644
--- a/test/stripe/file_upload_test.rb
+++ b/test/stripe/file_upload_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require File.expand_path("../../test_helper", __FILE__)
 
 module Stripe
diff --git a/test/stripe/invoice_item_test.rb b/test/stripe/invoice_item_test.rb
index b40ca8d66..04a0616aa 100644
--- a/test/stripe/invoice_item_test.rb
+++ b/test/stripe/invoice_item_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require File.expand_path("../../test_helper", __FILE__)
 
 module Stripe
diff --git a/test/stripe/invoice_line_item_test.rb b/test/stripe/invoice_line_item_test.rb
index 428fe7cb6..542902782 100644
--- a/test/stripe/invoice_line_item_test.rb
+++ b/test/stripe/invoice_line_item_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require File.expand_path("../../test_helper", __FILE__)
 
 module Stripe
diff --git a/test/stripe/invoice_test.rb b/test/stripe/invoice_test.rb
index dd145c033..ebf8582ad 100644
--- a/test/stripe/invoice_test.rb
+++ b/test/stripe/invoice_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require File.expand_path("../../test_helper", __FILE__)
 
 module Stripe
diff --git a/test/stripe/issuer_fraud_record_test.rb b/test/stripe/issuer_fraud_record_test.rb
index 1b0cc2021..b7462bbc6 100644
--- a/test/stripe/issuer_fraud_record_test.rb
+++ b/test/stripe/issuer_fraud_record_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require File.expand_path("../../test_helper", __FILE__)
 
 module Stripe
diff --git a/test/stripe/list_object_test.rb b/test/stripe/list_object_test.rb
index 296c8ff0f..a9b22ae59 100644
--- a/test/stripe/list_object_test.rb
+++ b/test/stripe/list_object_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require File.expand_path("../../test_helper", __FILE__)
 
 module Stripe
diff --git a/test/stripe/login_link_test.rb b/test/stripe/login_link_test.rb
index 56480a04c..b23397a35 100644
--- a/test/stripe/login_link_test.rb
+++ b/test/stripe/login_link_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require File.expand_path("../../test_helper", __FILE__)
 
 module Stripe
diff --git a/test/stripe/oauth_test.rb b/test/stripe/oauth_test.rb
index 12022d54d..33fcebec6 100644
--- a/test/stripe/oauth_test.rb
+++ b/test/stripe/oauth_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require File.expand_path("../../test_helper", __FILE__)
 
 module Stripe
diff --git a/test/stripe/order_return_test.rb b/test/stripe/order_return_test.rb
index d87f5ad36..2bc2578be 100644
--- a/test/stripe/order_return_test.rb
+++ b/test/stripe/order_return_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require File.expand_path("../../test_helper", __FILE__)
 
 module Stripe
diff --git a/test/stripe/order_test.rb b/test/stripe/order_test.rb
index 8c8258297..ed992f260 100644
--- a/test/stripe/order_test.rb
+++ b/test/stripe/order_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require File.expand_path("../../test_helper", __FILE__)
 
 module Stripe
diff --git a/test/stripe/payout_test.rb b/test/stripe/payout_test.rb
index 0b656c90c..e70f6ade7 100644
--- a/test/stripe/payout_test.rb
+++ b/test/stripe/payout_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require File.expand_path("../../test_helper", __FILE__)
 
 module Stripe
diff --git a/test/stripe/plan_test.rb b/test/stripe/plan_test.rb
index c22adf9d1..531b8ecee 100644
--- a/test/stripe/plan_test.rb
+++ b/test/stripe/plan_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require File.expand_path("../../test_helper", __FILE__)
 
 module Stripe
diff --git a/test/stripe/product_test.rb b/test/stripe/product_test.rb
index 997ce66bd..cff7512f7 100644
--- a/test/stripe/product_test.rb
+++ b/test/stripe/product_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require File.expand_path("../../test_helper", __FILE__)
 
 module Stripe
diff --git a/test/stripe/recipient_test.rb b/test/stripe/recipient_test.rb
index 8265c558f..990a5159d 100644
--- a/test/stripe/recipient_test.rb
+++ b/test/stripe/recipient_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require File.expand_path("../../test_helper", __FILE__)
 
 module Stripe
diff --git a/test/stripe/refund_test.rb b/test/stripe/refund_test.rb
index b82647c88..4708e0b77 100644
--- a/test/stripe/refund_test.rb
+++ b/test/stripe/refund_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require File.expand_path("../../test_helper", __FILE__)
 
 module Stripe
diff --git a/test/stripe/reversal_test.rb b/test/stripe/reversal_test.rb
index 757e6d318..a691866f6 100644
--- a/test/stripe/reversal_test.rb
+++ b/test/stripe/reversal_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require File.expand_path("../../test_helper", __FILE__)
 
 module Stripe
diff --git a/test/stripe/sku_test.rb b/test/stripe/sku_test.rb
index f97f67b42..3b0d3b4b5 100644
--- a/test/stripe/sku_test.rb
+++ b/test/stripe/sku_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require File.expand_path("../../test_helper", __FILE__)
 
 module Stripe
diff --git a/test/stripe/source_test.rb b/test/stripe/source_test.rb
index 33be36909..7a03aa5a7 100644
--- a/test/stripe/source_test.rb
+++ b/test/stripe/source_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require File.expand_path("../../test_helper", __FILE__)
 
 module Stripe
diff --git a/test/stripe/source_transaction_test.rb b/test/stripe/source_transaction_test.rb
index f5ce90c45..f7322cb66 100644
--- a/test/stripe/source_transaction_test.rb
+++ b/test/stripe/source_transaction_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require File.expand_path("../../test_helper", __FILE__)
 
 module Stripe
diff --git a/test/stripe/stripe_client_test.rb b/test/stripe/stripe_client_test.rb
index 137b7eaa2..c9ef34359 100644
--- a/test/stripe/stripe_client_test.rb
+++ b/test/stripe/stripe_client_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require File.expand_path("../../test_helper", __FILE__)
 
 module Stripe
diff --git a/test/stripe/stripe_object_test.rb b/test/stripe/stripe_object_test.rb
index a6c21a02b..aa18aba6f 100644
--- a/test/stripe/stripe_object_test.rb
+++ b/test/stripe/stripe_object_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require File.expand_path("../../test_helper", __FILE__)
 
 module Stripe
diff --git a/test/stripe/stripe_response_test.rb b/test/stripe/stripe_response_test.rb
index a24346977..025d6da62 100644
--- a/test/stripe/stripe_response_test.rb
+++ b/test/stripe/stripe_response_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require File.expand_path("../../test_helper", __FILE__)
 
 module Stripe
diff --git a/test/stripe/subscription_item_test.rb b/test/stripe/subscription_item_test.rb
index 08b37aa61..8033e0c68 100644
--- a/test/stripe/subscription_item_test.rb
+++ b/test/stripe/subscription_item_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require File.expand_path("../../test_helper", __FILE__)
 
 module Stripe
diff --git a/test/stripe/subscription_test.rb b/test/stripe/subscription_test.rb
index ecccf26db..d2c404097 100644
--- a/test/stripe/subscription_test.rb
+++ b/test/stripe/subscription_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require File.expand_path("../../test_helper", __FILE__)
 
 module Stripe
diff --git a/test/stripe/three_d_secure_test.rb b/test/stripe/three_d_secure_test.rb
index c9493cda1..5296e59a2 100644
--- a/test/stripe/three_d_secure_test.rb
+++ b/test/stripe/three_d_secure_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require File.expand_path("../../test_helper", __FILE__)
 
 module Stripe
diff --git a/test/stripe/topup_test.rb b/test/stripe/topup_test.rb
index 14d3c3d36..cd23ba7a8 100644
--- a/test/stripe/topup_test.rb
+++ b/test/stripe/topup_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require File.expand_path("../../test_helper", __FILE__)
 
 module Stripe
diff --git a/test/stripe/transfer_reversals_operations_test.rb b/test/stripe/transfer_reversals_operations_test.rb
index 5fb971178..3101223da 100644
--- a/test/stripe/transfer_reversals_operations_test.rb
+++ b/test/stripe/transfer_reversals_operations_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require File.expand_path("../../test_helper", __FILE__)
 
 module Stripe
diff --git a/test/stripe/transfer_test.rb b/test/stripe/transfer_test.rb
index 72de926a8..1f2c26078 100644
--- a/test/stripe/transfer_test.rb
+++ b/test/stripe/transfer_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require File.expand_path("../../test_helper", __FILE__)
 
 module Stripe
diff --git a/test/stripe/usage_record_test.rb b/test/stripe/usage_record_test.rb
index b2742fc22..c3e1f9b66 100644
--- a/test/stripe/usage_record_test.rb
+++ b/test/stripe/usage_record_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require File.expand_path("../../test_helper", __FILE__)
 
 module Stripe
diff --git a/test/stripe/util_test.rb b/test/stripe/util_test.rb
index 90b115ab6..a36ea1ede 100644
--- a/test/stripe/util_test.rb
+++ b/test/stripe/util_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require File.expand_path("../../test_helper", __FILE__)
 
 module Stripe
diff --git a/test/stripe/webhook_test.rb b/test/stripe/webhook_test.rb
index cf4990242..4f4ff4e78 100644
--- a/test/stripe/webhook_test.rb
+++ b/test/stripe/webhook_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require File.expand_path("../../test_helper", __FILE__)
 
 module Stripe
diff --git a/test/stripe_test.rb b/test/stripe_test.rb
index 0d6f53d80..571a8ac88 100644
--- a/test/stripe_test.rb
+++ b/test/stripe_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require File.expand_path("../test_helper", __FILE__)
 
 class StripeTest < Test::Unit::TestCase
diff --git a/test/test_data.rb b/test/test_data.rb
index 93c1184e9..d4f030d4f 100644
--- a/test/test_data.rb
+++ b/test/test_data.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Stripe
   module TestData
     def make_error(type, message)
diff --git a/test/test_helper.rb b/test/test_helper.rb
index ba3ec80d0..0a722c379 100644
--- a/test/test_helper.rb
+++ b/test/test_helper.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require "coveralls"
 Coveralls.wear!("test_frameworks")