diff --git a/Library/Homebrew/cli/args.rb b/Library/Homebrew/cli/args.rb
index 709a84e77f..648cd3aa71 100644
--- a/Library/Homebrew/cli/args.rb
+++ b/Library/Homebrew/cli/args.rb
@@ -19,9 +19,6 @@ module Homebrew
       sig { returns(T::Array[String]) }
       attr_reader :options_only, :flags_only
 
-      # undefine tap to allow --tap argument
-      undef tap
-
       sig { void }
       def initialize
         require "cli/named_args"
diff --git a/Library/Homebrew/extend/os/linux/cleanup.rb b/Library/Homebrew/extend/os/linux/cleanup.rb
index b6cd428fe8..deb231b318 100644
--- a/Library/Homebrew/extend/os/linux/cleanup.rb
+++ b/Library/Homebrew/extend/os/linux/cleanup.rb
@@ -2,8 +2,10 @@
 # frozen_string_literal: true
 
 module Homebrew
-  class Cleanup
-    undef use_system_ruby?
+  module CleanupLinux
+    extend T::Helpers
+
+    requires_ancestor { Cleanup }
 
     sig { returns(T::Boolean) }
     def use_system_ruby?
@@ -21,3 +23,5 @@ module Homebrew
     end
   end
 end
+
+Homebrew::Cleanup.prepend(Homebrew::CleanupLinux)
diff --git a/Library/Homebrew/extend/os/linux/formula.rb b/Library/Homebrew/extend/os/linux/formula.rb
index a6914a1f02..2d6250f816 100644
--- a/Library/Homebrew/extend/os/linux/formula.rb
+++ b/Library/Homebrew/extend/os/linux/formula.rb
@@ -1,12 +1,10 @@
 # typed: true # rubocop:disable Sorbet/StrictSigil
 # frozen_string_literal: true
 
-class Formula
-  undef shared_library
-  undef loader_path
-  undef deuniversalize_machos
-  undef add_global_deps_to_spec
-  undef valid_platform?
+module FormulaLinux
+  extend T::Helpers
+
+  requires_ancestor { Formula }
 
   sig { params(name: String, version: T.nilable(T.any(String, Integer))).returns(String) }
   def shared_library(name, version = nil)
@@ -50,3 +48,5 @@ class Formula
     requirements.none?(MacOSRequirement)
   end
 end
+
+Formula.prepend(FormulaLinux)
diff --git a/Library/Homebrew/extend/os/linux/parser.rb b/Library/Homebrew/extend/os/linux/parser.rb
index 7d81e2dddc..37f8481e18 100644
--- a/Library/Homebrew/extend/os/linux/parser.rb
+++ b/Library/Homebrew/extend/os/linux/parser.rb
@@ -1,16 +1,19 @@
-# typed: strict
+# typed: true # rubocop:todo Sorbet/StrictSigil
 # frozen_string_literal: true
 
 module Homebrew
   module CLI
-    class Parser
-      undef set_default_options
-      undef validate_options
+    module ParserLinux
+      extend T::Helpers
 
+      requires_ancestor { Homebrew::CLI::Parser }
+
+      sig { void }
       def set_default_options
         @args["formula?"] = true if @args.respond_to?(:formula?)
       end
 
+      sig { void }
       def validate_options
         return unless @args.respond_to?(:cask?)
         return unless @args.cask?
@@ -22,3 +25,5 @@ module Homebrew
     end
   end
 end
+
+Homebrew::CLI::Parser.prepend(Homebrew::CLI::ParserLinux)
diff --git a/Library/Homebrew/extend/os/mac/cleaner.rb b/Library/Homebrew/extend/os/mac/cleaner.rb
index 460169c996..23cdfbf947 100644
--- a/Library/Homebrew/extend/os/mac/cleaner.rb
+++ b/Library/Homebrew/extend/os/mac/cleaner.rb
@@ -1,13 +1,13 @@
 # typed: strict
 # frozen_string_literal: true
 
-class Cleaner
+module CleanerMac
   private
 
-  undef executable_path?
-
   sig { params(path: Pathname).returns(T::Boolean) }
   def executable_path?(path)
     path.mach_o_executable? || path.text_executable?
   end
 end
+
+Cleaner.prepend(CleanerMac)
diff --git a/Library/Homebrew/extend/os/mac/cleanup.rb b/Library/Homebrew/extend/os/mac/cleanup.rb
index 3565e162b4..8c07923e09 100644
--- a/Library/Homebrew/extend/os/mac/cleanup.rb
+++ b/Library/Homebrew/extend/os/mac/cleanup.rb
@@ -2,9 +2,7 @@
 # frozen_string_literal: true
 
 module Homebrew
-  class Cleanup
-    undef use_system_ruby?
-
+  module CleanupMac
     sig { returns(T::Boolean) }
     def use_system_ruby?
       return false if Homebrew::EnvConfig.force_vendor_ruby?
@@ -13,3 +11,5 @@ module Homebrew
     end
   end
 end
+
+Homebrew::Cleanup.prepend(Homebrew::CleanupMac)
diff --git a/Library/Homebrew/extend/os/mac/dev-cmd/bottle.rb b/Library/Homebrew/extend/os/mac/dev-cmd/bottle.rb
index 26d96cc1ce..1c3ad6a7f9 100644
--- a/Library/Homebrew/extend/os/mac/dev-cmd/bottle.rb
+++ b/Library/Homebrew/extend/os/mac/dev-cmd/bottle.rb
@@ -3,9 +3,7 @@
 
 module Homebrew
   module DevCmd
-    class Bottle < AbstractCommand
-      undef tar_args
-
+    module BottleMac
       sig { returns(T::Array[String]) }
       def tar_args
         if MacOS.version >= :catalina
@@ -15,8 +13,6 @@ module Homebrew
         end
       end
 
-      undef gnu_tar
-
       sig { params(gnu_tar_formula: Formula).returns(String) }
       def gnu_tar(gnu_tar_formula)
         "#{gnu_tar_formula.opt_bin}/gtar"
@@ -24,3 +20,5 @@ module Homebrew
     end
   end
 end
+
+Homebrew::DevCmd::Bottle.prepend(Homebrew::DevCmd::BottleMac)
diff --git a/Library/Homebrew/extend/os/mac/formula.rb b/Library/Homebrew/extend/os/mac/formula.rb
index c32a41d9e3..0aedbc9cab 100644
--- a/Library/Homebrew/extend/os/mac/formula.rb
+++ b/Library/Homebrew/extend/os/mac/formula.rb
@@ -1,9 +1,10 @@
 # typed: strict
 # frozen_string_literal: true
 
-class Formula
-  undef valid_platform?
-  undef std_cmake_args
+module FormulaMac
+  extend T::Helpers
+
+  requires_ancestor { Formula }
 
   sig { returns(T::Boolean) }
   def valid_platform?
@@ -31,3 +32,5 @@ class Formula
     args
   end
 end
+
+Formula.prepend(FormulaMac)
diff --git a/Library/Homebrew/extend/os/mac/formula_installer.rb b/Library/Homebrew/extend/os/mac/formula_installer.rb
index 89115c871d..fe825f7221 100644
--- a/Library/Homebrew/extend/os/mac/formula_installer.rb
+++ b/Library/Homebrew/extend/os/mac/formula_installer.rb
@@ -1,8 +1,10 @@
 # typed: strict
 # frozen_string_literal: true
 
-class FormulaInstaller
-  undef fresh_install?
+module FormulaInstallerMac
+  extend T::Helpers
+
+  requires_ancestor { FormulaInstaller }
 
   sig { params(formula: Formula).returns(T.nilable(T::Boolean)) }
   def fresh_install?(formula)
@@ -10,3 +12,5 @@ class FormulaInstaller
       (!installed_as_dependency? || !formula.any_version_installed?)
   end
 end
+
+FormulaInstaller.prepend(FormulaInstallerMac)
diff --git a/Library/Homebrew/extend/os/mac/linkage_checker.rb b/Library/Homebrew/extend/os/mac/linkage_checker.rb
index b48d2b90d3..1171257479 100644
--- a/Library/Homebrew/extend/os/mac/linkage_checker.rb
+++ b/Library/Homebrew/extend/os/mac/linkage_checker.rb
@@ -1,9 +1,7 @@
 # typed: strict
 # frozen_string_literal: true
 
-class LinkageChecker
-  undef system_libraries_exist_in_cache?
-
+module LinkageCheckerMac
   private
 
   sig { returns(T::Boolean) }
@@ -12,3 +10,5 @@ class LinkageChecker
     MacOS.version >= :big_sur
   end
 end
+
+LinkageChecker.prepend(LinkageCheckerMac)
diff --git a/Library/Homebrew/extend/os/mac/readall.rb b/Library/Homebrew/extend/os/mac/readall.rb
index 6957c2b086..15a78a78fe 100644
--- a/Library/Homebrew/extend/os/mac/readall.rb
+++ b/Library/Homebrew/extend/os/mac/readall.rb
@@ -1,39 +1,42 @@
 # typed: strict
 # frozen_string_literal: true
 
-module Readall
-  class << self
-    undef valid_casks?
+module ReadallMac
+  extend T::Helpers
 
-    def valid_casks?(tap, os_name: nil, arch: Hardware::CPU.type)
-      return true if os_name == :linux
+  requires_ancestor { Kernel }
 
-      current_macos_version = if os_name.is_a?(Symbol)
-        MacOSVersion.from_symbol(os_name)
-      else
-        MacOS.version
-      end
+  sig { params(tap: Tap, os_name: T.nilable(Symbol), arch: T.nilable(Symbol)).returns(T::Boolean) }
+  def valid_casks?(tap, os_name: nil, arch: Hardware::CPU.type)
+    return true if os_name == :linux
 
-      success = T.let(true, T::Boolean)
-      tap.cask_files.each do |file|
-        cask = Cask::CaskLoader.load(file)
-
-        # Fine to have missing URLs for unsupported macOS
-        macos_req = cask.depends_on.macos
-        next if macos_req&.version && Array(macos_req.version).none? do |macos_version|
-          current_macos_version.compare(macos_req.comparator, macos_version)
-        end
-
-        raise "Missing URL" if cask.url.nil?
-      rescue Interrupt
-        raise
-      rescue Exception => e # rubocop:disable Lint/RescueException
-        os_and_arch = "macOS #{current_macos_version} on #{arch}"
-        onoe "Invalid cask (#{os_and_arch}): #{file}"
-        $stderr.puts e
-        success = false
-      end
-      success
+    current_macos_version = if os_name.is_a?(Symbol)
+      MacOSVersion.from_symbol(os_name)
+    else
+      MacOS.version
     end
+
+    success = T.let(true, T::Boolean)
+    tap.cask_files.each do |file|
+      cask = Cask::CaskLoader.load(file)
+
+      # Fine to have missing URLs for unsupported macOS
+      macos_req = cask.depends_on.macos
+      next if macos_req&.version && Array(macos_req.version).none? do |macos_version|
+        current_macos_version.compare(macos_req.comparator, macos_version)
+      end
+
+      raise "Missing URL" if cask.url.nil?
+    rescue Interrupt
+      raise
+    rescue Exception => e # rubocop:disable Lint/RescueException
+      os_and_arch = "macOS #{current_macos_version} on #{arch}"
+      onoe "Invalid cask (#{os_and_arch}): #{file}"
+      $stderr.puts e
+      success = false
+    end
+    success
   end
 end
+
+Readall.singleton_class.prepend(ReadallMac)
diff --git a/Library/Homebrew/extend/os/mac/simulate_system.rb b/Library/Homebrew/extend/os/mac/simulate_system.rb
index 95bc2ef9ae..aacc269202 100644
--- a/Library/Homebrew/extend/os/mac/simulate_system.rb
+++ b/Library/Homebrew/extend/os/mac/simulate_system.rb
@@ -2,20 +2,17 @@
 # frozen_string_literal: true
 
 module Homebrew
-  class SimulateSystem
-    class << self
-      undef simulating_or_running_on_macos?
-      undef current_os
+  module SimulateSystemMac
+    sig { returns(T::Boolean) }
+    def simulating_or_running_on_macos?
+      SimulateSystem.os.blank? || [:macos, *MacOSVersion::SYMBOLS.keys].include?(SimulateSystem.os)
+    end
 
-      sig { returns(T::Boolean) }
-      def simulating_or_running_on_macos?
-        os.blank? || [:macos, *MacOSVersion::SYMBOLS.keys].include?(os)
-      end
-
-      sig { returns(Symbol) }
-      def current_os
-        os || MacOS.version.to_sym
-      end
+    sig { returns(Symbol) }
+    def current_os
+      SimulateSystem.os || MacOS.version.to_sym
     end
   end
 end
+
+Homebrew::SimulateSystem.singleton_class.prepend(Homebrew::SimulateSystemMac)