diff --git a/Appraisals b/Appraisals
index 5809374..f9dbc8e 100644
--- a/Appraisals
+++ b/Appraisals
@@ -1,5 +1,14 @@
 # frozen_string_literal: true
 
+# HACK: This uses odd syntax to make appraisal customization work on newer Rubies.
+# See https://github.com/thoughtbot/appraisal/pull/214. Once that one has been
+# released, we should use customize_gemfiles instead.
+Customize.new heading: <<~HEADING.chomp
+  frozen_string_literal: true
+
+  This file was generated by Appraisal
+HEADING
+
 appraise "active_record_61" do
   gem "activerecord", "~> 6.1.0", require: "active_record"
   gem "activesupport", "~> 6.1.0", require: "active_support"
diff --git a/gemfiles/active_record_61.gemfile b/gemfiles/active_record_61.gemfile
index 6a71123..1d1773a 100644
--- a/gemfiles/active_record_61.gemfile
+++ b/gemfiles/active_record_61.gemfile
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # This file was generated by Appraisal
 
 source "https://rubygems.org"
diff --git a/gemfiles/active_record_70.gemfile b/gemfiles/active_record_70.gemfile
index f9a39a7..335f68b 100644
--- a/gemfiles/active_record_70.gemfile
+++ b/gemfiles/active_record_70.gemfile
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # This file was generated by Appraisal
 
 source "https://rubygems.org"
diff --git a/gemfiles/active_record_71.gemfile b/gemfiles/active_record_71.gemfile
index 15584c3..c4469c7 100644
--- a/gemfiles/active_record_71.gemfile
+++ b/gemfiles/active_record_71.gemfile
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # This file was generated by Appraisal
 
 source "https://rubygems.org"
diff --git a/gemfiles/active_record_72.gemfile b/gemfiles/active_record_72.gemfile
index afdd205..9d5bcbb 100644
--- a/gemfiles/active_record_72.gemfile
+++ b/gemfiles/active_record_72.gemfile
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # This file was generated by Appraisal
 
 source "https://rubygems.org"
diff --git a/test/legacy/validations_test.rb b/test/legacy/validations_test.rb
index 673829f..4a30107 100644
--- a/test/legacy/validations_test.rb
+++ b/test/legacy/validations_test.rb
@@ -20,8 +20,7 @@ class ParanoidWithSerializedColumn < ActiveRecord::Base
     acts_as_paranoid
     validates_as_paranoid
 
-    
-    if Gem::Version.new(ActiveRecord::VERSION::STRING) < Gem::Version.new('7.2')
+    if Gem::Version.new(ActiveRecord::VERSION::STRING) < Gem::Version.new("7.2")
       serialize :colors, Array
     else
       serialize :colors