diff --git a/db/migrate/20190510055357_migrate_steam_auth_data.rb b/db/migrate/20190510055357_migrate_steam_auth_data.rb
index c35e91d..fda5b07 100644
--- a/db/migrate/20190510055357_migrate_steam_auth_data.rb
+++ b/db/migrate/20190510055357_migrate_steam_auth_data.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class MigrateSteamAuthData < ActiveRecord::Migration[5.2]
   def up
     execute <<~SQL
diff --git a/lib/auth/steam_authenticator.rb b/lib/auth/steam_authenticator.rb
index 67fe865..87b9e9c 100644
--- a/lib/auth/steam_authenticator.rb
+++ b/lib/auth/steam_authenticator.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Auth::SteamAuthenticator < ::Auth::ManagedAuthenticator
   def name
     'steam'
diff --git a/lib/validators/enable_steam_logins_validator.rb b/lib/validators/enable_steam_logins_validator.rb
index 9196f9e..fcf208b 100644
--- a/lib/validators/enable_steam_logins_validator.rb
+++ b/lib/validators/enable_steam_logins_validator.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class EnableSteamLoginsValidator
   def initialize(opts = {})
     @opts = opts
diff --git a/plugin.rb b/plugin.rb
index 4810f6b..ee367dd 100644
--- a/plugin.rb
+++ b/plugin.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # name: Steam authentication with Discourse
 # about: Authenticate with Discourse with Steam
 # version: 2.0.1