diff --git a/Library/Homebrew/attestation.rb b/Library/Homebrew/attestation.rb
index f568a495ded36..853643465fa30 100644
--- a/Library/Homebrew/attestation.rb
+++ b/Library/Homebrew/attestation.rb
@@ -60,7 +60,7 @@ def self.enabled?
       return false if Homebrew::EnvConfig.no_verify_attestations?
       return true if Homebrew::EnvConfig.verify_attestations?
       return false if ENV.fetch("CI", false)
-      return false if ::OS.unsupported_configuration?
+      return false if OS.unsupported_configuration?
 
       # Always check credentials last to avoid unnecessary credential extraction.
       (Homebrew::EnvConfig.developer? || Homebrew::EnvConfig.devcmdrun?) && GitHub::API.credentials.present?
diff --git a/Library/Homebrew/dev-cmd/bottle.rb b/Library/Homebrew/dev-cmd/bottle.rb
index 5ce69ba9fde07..b0c914ae01d39 100644
--- a/Library/Homebrew/dev-cmd/bottle.rb
+++ b/Library/Homebrew/dev-cmd/bottle.rb
@@ -394,10 +394,10 @@ def formula_ignores(formula)
         # On Linux, GCC installation can be moved so long as the whole directory tree is moved together:
         # https://gcc-help.gcc.gnu.narkive.com/GnwuCA7l/moving-gcc-from-the-installation-path-is-it-allowed.
         when Version.formula_optionally_versioned_regex(:gcc)
-          Regexp.union(%r{#{cellar_regex}/gcc}, %r{#{prefix_regex}/opt/gcc}) if ::OS.linux?
+          Regexp.union(%r{#{cellar_regex}/gcc}, %r{#{prefix_regex}/opt/gcc}) if OS.linux?
         # binutils is relocatable for the same reason: https://github.com/Homebrew/brew/pull/11899#issuecomment-906804451.
         when Version.formula_optionally_versioned_regex(:binutils)
-          %r{#{cellar_regex}/binutils} if ::OS.linux?
+          %r{#{cellar_regex}/binutils} if OS.linux?
         end
         # rubocop:enable Homebrew/MoveToExtendOS
 
diff --git a/Library/Homebrew/dev-cmd/tests.rb b/Library/Homebrew/dev-cmd/tests.rb
index ec64bdde394ba..b45df9ac942d7 100644
--- a/Library/Homebrew/dev-cmd/tests.rb
+++ b/Library/Homebrew/dev-cmd/tests.rb
@@ -116,12 +116,12 @@ def run
 
           # TODO: Refactor and move to extend/os
           # rubocop:disable Homebrew/MoveToExtendOS
-          unless ::OS.mac?
+          unless OS.mac?
             bundle_args << "--tag" << "~needs_macos" << "--tag" << "~cask"
             files = files.grep_v(%r{^test/(os/mac|cask)(/.*|_spec\.rb)$})
           end
 
-          unless ::OS.linux?
+          unless OS.linux?
             bundle_args << "--tag" << "~needs_linux"
             files = files.grep_v(%r{^test/os/linux(/.*|_spec\.rb)$})
           end
diff --git a/Library/Homebrew/extend/os/linux/cleanup.rb b/Library/Homebrew/extend/os/linux/cleanup.rb
index 15a7e0b0ecac6..be63e0e558298 100644
--- a/Library/Homebrew/extend/os/linux/cleanup.rb
+++ b/Library/Homebrew/extend/os/linux/cleanup.rb
@@ -1,31 +1,29 @@
 # typed: strict
 # frozen_string_literal: true
 
-module Homebrew
-  module OS
-    module Linux
-      module Cleanup
-        extend T::Helpers
+module OS
+  module Linux
+    module Cleanup
+      extend T::Helpers
 
-        requires_ancestor { Homebrew::Cleanup }
+      requires_ancestor { Homebrew::Cleanup }
 
-        sig { returns(T::Boolean) }
-        def use_system_ruby?
-          return false if Homebrew::EnvConfig.force_vendor_ruby?
+      sig { returns(T::Boolean) }
+      def use_system_ruby?
+        return false if Homebrew::EnvConfig.force_vendor_ruby?
 
-          rubies = [which("ruby"), which("ruby", ORIGINAL_PATHS)].compact
-          system_ruby = Pathname.new("/usr/bin/ruby")
-          rubies << system_ruby if system_ruby.exist?
+        rubies = [which("ruby"), which("ruby", ORIGINAL_PATHS)].compact
+        system_ruby = Pathname.new("/usr/bin/ruby")
+        rubies << system_ruby if system_ruby.exist?
 
-          check_ruby_version = HOMEBREW_LIBRARY_PATH/"utils/ruby_check_version_script.rb"
-          rubies.uniq.any? do |ruby|
-            quiet_system ruby, "--enable-frozen-string-literal", "--disable=gems,did_you_mean,rubyopt",
-                         check_ruby_version, RUBY_VERSION
-          end
+        check_ruby_version = HOMEBREW_LIBRARY_PATH/"utils/ruby_check_version_script.rb"
+        rubies.uniq.any? do |ruby|
+          quiet_system ruby, "--enable-frozen-string-literal", "--disable=gems,did_you_mean,rubyopt",
+                       check_ruby_version, RUBY_VERSION
         end
       end
     end
   end
 end
 
-Homebrew::Cleanup.prepend(Homebrew::OS::Linux::Cleanup)
+Homebrew::Cleanup.prepend(OS::Linux::Cleanup)
diff --git a/Library/Homebrew/extend/os/linux/cli/parser.rb b/Library/Homebrew/extend/os/linux/cli/parser.rb
index 091ad48920ff7..e5fd59e146cb9 100644
--- a/Library/Homebrew/extend/os/linux/cli/parser.rb
+++ b/Library/Homebrew/extend/os/linux/cli/parser.rb
@@ -1,33 +1,31 @@
 # typed: strict
 # frozen_string_literal: true
 
-module Homebrew
-  module OS
-    module Linux
-      module CLI
-        module Parser
-          extend T::Helpers
+module OS
+  module Linux
+    module CLI
+      module Parser
+        extend T::Helpers
 
-          requires_ancestor { Homebrew::CLI::Parser }
+        requires_ancestor { Homebrew::CLI::Parser }
 
-          sig { void }
-          def set_default_options
-            args["formula?"] = true if args.respond_to?(:formula?)
-          end
+        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?
+        sig { void }
+        def validate_options
+          return unless args.respond_to?(:cask?)
+          return unless args.cask?
 
-            # NOTE: We don't raise an error here because we don't want
-            #       to print the help page or a stack trace.
-            odie "Invalid `--cask` usage: Casks do not work on Linux"
-          end
+          # NOTE: We don't raise an error here because we don't want
+          #       to print the help page or a stack trace.
+          odie "Invalid `--cask` usage: Casks do not work on Linux"
         end
       end
     end
   end
 end
 
-Homebrew::CLI::Parser.prepend(Homebrew::OS::Linux::CLI::Parser)
+Homebrew::CLI::Parser.prepend(OS::Linux::CLI::Parser)
diff --git a/Library/Homebrew/extend/os/linux/diagnostic.rb b/Library/Homebrew/extend/os/linux/diagnostic.rb
index 84d8ee6167972..c3c665cb20a8c 100644
--- a/Library/Homebrew/extend/os/linux/diagnostic.rb
+++ b/Library/Homebrew/extend/os/linux/diagnostic.rb
@@ -95,11 +95,11 @@ def check_supported_architecture
       end
 
       def check_glibc_minimum_version
-        return unless ::OS::Linux::Glibc.below_minimum_version?
+        return unless OS::Linux::Glibc.below_minimum_version?
 
         <<~EOS
-          Your system glibc #{::OS::Linux::Glibc.system_version} is too old.
-          We only support glibc #{::OS::Linux::Glibc.minimum_version} or later.
+          Your system glibc #{OS::Linux::Glibc.system_version} is too old.
+          We only support glibc #{OS::Linux::Glibc.minimum_version} or later.
           #{please_create_pull_requests}
           We recommend updating to a newer version via your distribution's
           package manager, upgrading your distribution to the latest version,
@@ -108,11 +108,11 @@ def check_glibc_minimum_version
       end
 
       def check_kernel_minimum_version
-        return unless ::OS::Linux::Kernel.below_minimum_version?
+        return unless OS::Linux::Kernel.below_minimum_version?
 
         <<~EOS
-          Your Linux kernel #{::OS.kernel_version} is too old.
-          We only support kernel #{::OS::Linux::Kernel.minimum_version} or later.
+          Your Linux kernel #{OS.kernel_version} is too old.
+          We only support kernel #{OS::Linux::Kernel.minimum_version} or later.
           You will be unable to use binary packages (bottles).
           #{please_create_pull_requests}
           We recommend updating to a newer version via your distribution's
diff --git a/Library/Homebrew/extend/os/linux/formula.rb b/Library/Homebrew/extend/os/linux/formula.rb
index e71b1e7df109f..4af57d02c9eef 100644
--- a/Library/Homebrew/extend/os/linux/formula.rb
+++ b/Library/Homebrew/extend/os/linux/formula.rb
@@ -1,58 +1,56 @@
 # typed: true # rubocop:disable Sorbet/StrictSigil
 # frozen_string_literal: true
 
-module Homebrew
-  module OS
-    module Linux
-      module Formula
-        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)
-          suffix = if version == "*" || (name == "*" && version.blank?)
-            "{,.*}"
-          elsif version.present?
-            ".#{version}"
-          end
-          "#{name}.so#{suffix}"
+module OS
+  module Linux
+    module Formula
+      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)
+        suffix = if version == "*" || (name == "*" && version.blank?)
+          "{,.*}"
+        elsif version.present?
+          ".#{version}"
         end
+        "#{name}.so#{suffix}"
+      end
 
-        sig { returns(String) }
-        def loader_path
-          "$ORIGIN"
-        end
+      sig { returns(String) }
+      def loader_path
+        "$ORIGIN"
+      end
 
-        sig { params(targets: T.nilable(T.any(Pathname, String))).void }
-        def deuniversalize_machos(*targets); end
-
-        sig { params(spec: SoftwareSpec).void }
-        def add_global_deps_to_spec(spec)
-          return unless DevelopmentTools.needs_build_formulae?
-
-          @global_deps ||= begin
-            dependency_collector = spec.dependency_collector
-            related_formula_names = Set.new([
-              name,
-              *aliases,
-              *versioned_formulae_names,
-            ])
-            [
-              dependency_collector.gcc_dep_if_needed(related_formula_names),
-              dependency_collector.glibc_dep_if_needed(related_formula_names),
-            ].compact.freeze
-          end
-          @global_deps.each { |dep| spec.dependency_collector.add(dep) }
+      sig { params(targets: T.nilable(T.any(Pathname, String))).void }
+      def deuniversalize_machos(*targets); end
+
+      sig { params(spec: SoftwareSpec).void }
+      def add_global_deps_to_spec(spec)
+        return unless DevelopmentTools.needs_build_formulae?
+
+        @global_deps ||= begin
+          dependency_collector = spec.dependency_collector
+          related_formula_names = Set.new([
+            name,
+            *aliases,
+            *versioned_formulae_names,
+          ])
+          [
+            dependency_collector.gcc_dep_if_needed(related_formula_names),
+            dependency_collector.glibc_dep_if_needed(related_formula_names),
+          ].compact.freeze
         end
+        @global_deps.each { |dep| spec.dependency_collector.add(dep) }
+      end
 
-        sig { returns(T::Boolean) }
-        def valid_platform?
-          requirements.none?(MacOSRequirement)
-        end
+      sig { returns(T::Boolean) }
+      def valid_platform?
+        requirements.none?(MacOSRequirement)
       end
     end
   end
 end
 
-Formula.prepend(Homebrew::OS::Linux::Formula)
+Formula.prepend(OS::Linux::Formula)
diff --git a/Library/Homebrew/extend/os/linux/install.rb b/Library/Homebrew/extend/os/linux/install.rb
index 2ce522d91cd66..ab4a4901466bd 100644
--- a/Library/Homebrew/extend/os/linux/install.rb
+++ b/Library/Homebrew/extend/os/linux/install.rb
@@ -78,7 +78,7 @@ def self.symlink_ld_so
     private_class_method :symlink_ld_so
 
     def self.setup_preferred_gcc_libs
-      gcc_opt_prefix = HOMEBREW_PREFIX/"opt/#{::OS::LINUX_PREFERRED_GCC_RUNTIME_FORMULA}"
+      gcc_opt_prefix = HOMEBREW_PREFIX/"opt/#{OS::LINUX_PREFERRED_GCC_RUNTIME_FORMULA}"
       glibc_installed = (HOMEBREW_PREFIX/"opt/glibc/bin/ld.so").readable?
 
       return unless gcc_opt_prefix.readable?
diff --git a/Library/Homebrew/extend/os/mac/cleaner.rb b/Library/Homebrew/extend/os/mac/cleaner.rb
index ece95188cc884..303500fa5e1f6 100644
--- a/Library/Homebrew/extend/os/mac/cleaner.rb
+++ b/Library/Homebrew/extend/os/mac/cleaner.rb
@@ -1,19 +1,17 @@
 # typed: strict
 # frozen_string_literal: true
 
-module Homebrew
-  module OS
-    module MacOS
-      module Cleaner
-        private
+module OS
+  module Mac
+    module Cleaner
+      private
 
-        sig { params(path: Pathname).returns(T::Boolean) }
-        def executable_path?(path)
-          path.mach_o_executable? || path.text_executable?
-        end
+      sig { params(path: Pathname).returns(T::Boolean) }
+      def executable_path?(path)
+        path.mach_o_executable? || path.text_executable?
       end
     end
   end
 end
 
-Cleaner.prepend(Homebrew::OS::MacOS::Cleaner)
+Cleaner.prepend(OS::Mac::Cleaner)
diff --git a/Library/Homebrew/extend/os/mac/cleanup.rb b/Library/Homebrew/extend/os/mac/cleanup.rb
index 75d32bea15904..08b4ec01454d2 100644
--- a/Library/Homebrew/extend/os/mac/cleanup.rb
+++ b/Library/Homebrew/extend/os/mac/cleanup.rb
@@ -1,19 +1,17 @@
 # typed: strict
 # frozen_string_literal: true
 
-module Homebrew
-  module OS
-    module MacOS
-      module Cleanup
-        sig { returns(T::Boolean) }
-        def use_system_ruby?
-          return false if Homebrew::EnvConfig.force_vendor_ruby?
+module OS
+  module Mac
+    module Cleanup
+      sig { returns(T::Boolean) }
+      def use_system_ruby?
+        return false if Homebrew::EnvConfig.force_vendor_ruby?
 
-          Homebrew::EnvConfig.developer? && ENV["HOMEBREW_USE_RUBY_FROM_PATH"].present?
-        end
+        Homebrew::EnvConfig.developer? && ENV["HOMEBREW_USE_RUBY_FROM_PATH"].present?
       end
     end
   end
 end
 
-Homebrew::Cleanup.prepend(Homebrew::OS::MacOS::Cleanup)
+Homebrew::Cleanup.prepend(OS::Mac::Cleanup)
diff --git a/Library/Homebrew/extend/os/mac/dev-cmd/bottle.rb b/Library/Homebrew/extend/os/mac/dev-cmd/bottle.rb
index c7ebdc5e4469e..9d07b436956cd 100644
--- a/Library/Homebrew/extend/os/mac/dev-cmd/bottle.rb
+++ b/Library/Homebrew/extend/os/mac/dev-cmd/bottle.rb
@@ -1,28 +1,26 @@
 # typed: strict
 # frozen_string_literal: true
 
-module Homebrew
-  module OS
-    module MacOS
-      module DevCmd
-        module Bottle
-          sig { returns(T::Array[String]) }
-          def tar_args
-            if ::MacOS.version >= :catalina
-              ["--no-mac-metadata", "--no-acls", "--no-xattrs"].freeze
-            else
-              [].freeze
-            end
+module OS
+  module Mac
+    module DevCmd
+      module Bottle
+        sig { returns(T::Array[String]) }
+        def tar_args
+          if MacOS.version >= :catalina
+            ["--no-mac-metadata", "--no-acls", "--no-xattrs"].freeze
+          else
+            [].freeze
           end
+        end
 
-          sig { params(gnu_tar_formula: Formula).returns(String) }
-          def gnu_tar(gnu_tar_formula)
-            "#{gnu_tar_formula.opt_bin}/gtar"
-          end
+        sig { params(gnu_tar_formula: Formula).returns(String) }
+        def gnu_tar(gnu_tar_formula)
+          "#{gnu_tar_formula.opt_bin}/gtar"
         end
       end
     end
   end
 end
 
-Homebrew::DevCmd::Bottle.prepend(Homebrew::OS::MacOS::DevCmd::Bottle)
+Homebrew::DevCmd::Bottle.prepend(OS::Mac::DevCmd::Bottle)
diff --git a/Library/Homebrew/extend/os/mac/diagnostic.rb b/Library/Homebrew/extend/os/mac/diagnostic.rb
index 86fe60c347af6..fa714f68ec56e 100644
--- a/Library/Homebrew/extend/os/mac/diagnostic.rb
+++ b/Library/Homebrew/extend/os/mac/diagnostic.rb
@@ -110,9 +110,9 @@ def check_for_unsupported_macos
         return if ENV["HOMEBREW_INTEGRATION_TEST"]
 
         who = +"We"
-        what = if ::OS::Mac.version.prerelease?
+        what = if OS::Mac.version.prerelease?
           "pre-release version"
-        elsif ::OS::Mac.version.outdated_release?
+        elsif OS::Mac.version.outdated_release?
           who << " (and Apple)"
           "old version"
         end
@@ -149,7 +149,7 @@ def check_xcode_up_to_date
           #{MacOS::Xcode.update_instructions}
         EOS
 
-        if ::OS::Mac.version.prerelease?
+        if OS::Mac.version.prerelease?
           current_path = Utils.popen_read("/usr/bin/xcode-select", "-p")
           message += <<~EOS
             If #{MacOS::Xcode.latest_version} is installed, you may need to:
diff --git a/Library/Homebrew/extend/os/mac/formula.rb b/Library/Homebrew/extend/os/mac/formula.rb
index 7cfd0a88f9a74..4731717dfe475 100644
--- a/Library/Homebrew/extend/os/mac/formula.rb
+++ b/Library/Homebrew/extend/os/mac/formula.rb
@@ -1,41 +1,39 @@
 # typed: strict
 # frozen_string_literal: true
 
-module Homebrew
-  module OS
-    module MacOS
-      module Formula
-        extend T::Helpers
-
-        requires_ancestor { ::Formula }
-
-        sig { returns(T::Boolean) }
-        def valid_platform?
-          requirements.none?(LinuxRequirement)
-        end
-
-        sig {
-          params(
-            install_prefix: T.any(String, Pathname),
-            install_libdir: T.any(String, Pathname),
-            find_framework: String,
-          ).returns(T::Array[String])
-        }
-        def std_cmake_args(install_prefix: prefix, install_libdir: "lib", find_framework: "LAST")
-          args = generic_std_cmake_args(install_prefix:, install_libdir:, find_framework:)
-
-          # Avoid false positives for clock_gettime support on 10.11.
-          # CMake cache entries for other weak symbols may be added here as needed.
-          args << "-DHAVE_CLOCK_GETTIME:INTERNAL=0" if ::MacOS.version == "10.11" && ::MacOS::Xcode.version >= "8.0"
-
-          # Ensure CMake is using the same SDK we are using.
-          args << "-DCMAKE_OSX_SYSROOT=#{::MacOS.sdk_for_formula(self).path}" if ::MacOS.sdk_root_needed?
-
-          args
-        end
+module OS
+  module Mac
+    module Formula
+      extend T::Helpers
+
+      requires_ancestor { ::Formula }
+
+      sig { returns(T::Boolean) }
+      def valid_platform?
+        requirements.none?(LinuxRequirement)
+      end
+
+      sig {
+        params(
+          install_prefix: T.any(String, Pathname),
+          install_libdir: T.any(String, Pathname),
+          find_framework: String,
+        ).returns(T::Array[String])
+      }
+      def std_cmake_args(install_prefix: prefix, install_libdir: "lib", find_framework: "LAST")
+        args = generic_std_cmake_args(install_prefix:, install_libdir:, find_framework:)
+
+        # Avoid false positives for clock_gettime support on 10.11.
+        # CMake cache entries for other weak symbols may be added here as needed.
+        args << "-DHAVE_CLOCK_GETTIME:INTERNAL=0" if MacOS.version == "10.11" && MacOS::Xcode.version >= "8.0"
+
+        # Ensure CMake is using the same SDK we are using.
+        args << "-DCMAKE_OSX_SYSROOT=#{MacOS.sdk_for_formula(self).path}" if MacOS.sdk_root_needed?
+
+        args
       end
     end
   end
 end
 
-Formula.prepend(Homebrew::OS::MacOS::Formula)
+Formula.prepend(OS::Mac::Formula)
diff --git a/Library/Homebrew/extend/os/mac/formula_installer.rb b/Library/Homebrew/extend/os/mac/formula_installer.rb
index b601cbad93bc5..a817d924fb061 100644
--- a/Library/Homebrew/extend/os/mac/formula_installer.rb
+++ b/Library/Homebrew/extend/os/mac/formula_installer.rb
@@ -1,22 +1,20 @@
 # typed: strict
 # frozen_string_literal: true
 
-module Homebrew
-  module OS
-    module MacOS
-      module FormulaInstaller
-        extend T::Helpers
+module OS
+  module Mac
+    module FormulaInstaller
+      extend T::Helpers
 
-        requires_ancestor { ::FormulaInstaller }
+      requires_ancestor { ::FormulaInstaller }
 
-        sig { params(formula: Formula).returns(T.nilable(T::Boolean)) }
-        def fresh_install?(formula)
-          !Homebrew::EnvConfig.developer? && !::OS::Mac.version.outdated_release? &&
-            (!installed_as_dependency? || !formula.any_version_installed?)
-        end
+      sig { params(formula: Formula).returns(T.nilable(T::Boolean)) }
+      def fresh_install?(formula)
+        !Homebrew::EnvConfig.developer? && !OS::Mac.version.outdated_release? &&
+          (!installed_as_dependency? || !formula.any_version_installed?)
       end
     end
   end
 end
 
-FormulaInstaller.prepend(Homebrew::OS::MacOS::FormulaInstaller)
+FormulaInstaller.prepend(OS::Mac::FormulaInstaller)
diff --git a/Library/Homebrew/extend/os/mac/linkage_checker.rb b/Library/Homebrew/extend/os/mac/linkage_checker.rb
index 6a63b0aefc0d8..b82af034b2121 100644
--- a/Library/Homebrew/extend/os/mac/linkage_checker.rb
+++ b/Library/Homebrew/extend/os/mac/linkage_checker.rb
@@ -1,20 +1,18 @@
 # typed: strict
 # frozen_string_literal: true
 
-module Homebrew
-  module OS
-    module MacOS
-      module LinkageChecker
-        private
+module OS
+  module Mac
+    module LinkageChecker
+      private
 
-        sig { returns(T::Boolean) }
-        def system_libraries_exist_in_cache?
-          # In macOS Big Sur and later, system libraries do not exist on-disk and instead exist in a cache.
-          ::MacOS.version >= :big_sur
-        end
+      sig { returns(T::Boolean) }
+      def system_libraries_exist_in_cache?
+        # In macOS Big Sur and later, system libraries do not exist on-disk and instead exist in a cache.
+        MacOS.version >= :big_sur
       end
     end
   end
 end
 
-LinkageChecker.prepend(Homebrew::OS::MacOS::LinkageChecker)
+LinkageChecker.prepend(OS::Mac::LinkageChecker)
diff --git a/Library/Homebrew/extend/os/mac/readall.rb b/Library/Homebrew/extend/os/mac/readall.rb
index 008c036bd7985..4ad0cd1a05f2f 100644
--- a/Library/Homebrew/extend/os/mac/readall.rb
+++ b/Library/Homebrew/extend/os/mac/readall.rb
@@ -1,48 +1,46 @@
 # typed: strict
 # frozen_string_literal: true
 
-module Homebrew
-  module OS
-    module MacOS
-      module Readall
-        extend T::Helpers
-
-        requires_ancestor { Kernel }
-
-        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
-
-          current_macos_version = if os_name.is_a?(Symbol)
-            MacOSVersion.from_symbol(os_name)
-          else
-            ::MacOS.version
-          end
+module OS
+  module Mac
+    module Readall
+      extend T::Helpers
+
+      requires_ancestor { Kernel }
 
-          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
+      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
+
+        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
-          success
+
+          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
   end
 end
 
-Readall.singleton_class.prepend(Homebrew::OS::MacOS::Readall)
+Readall.singleton_class.prepend(OS::Mac::Readall)
diff --git a/Library/Homebrew/extend/os/mac/simulate_system.rb b/Library/Homebrew/extend/os/mac/simulate_system.rb
index ac63e8568f1d6..f027eb0b883c6 100644
--- a/Library/Homebrew/extend/os/mac/simulate_system.rb
+++ b/Library/Homebrew/extend/os/mac/simulate_system.rb
@@ -1,23 +1,21 @@
 # typed: strict
 # frozen_string_literal: true
 
-module Homebrew
-  module OS
-    module MacOS
-      module SimulateSystem
-        sig { returns(T::Boolean) }
-        def simulating_or_running_on_macos?
-          Homebrew::SimulateSystem.os.blank? || [:macos,
-                                                 *MacOSVersion::SYMBOLS.keys].include?(Homebrew::SimulateSystem.os)
-        end
+module OS
+  module Mac
+    module SimulateSystem
+      sig { returns(T::Boolean) }
+      def simulating_or_running_on_macos?
+        Homebrew::SimulateSystem.os.blank? || [:macos,
+                                               *MacOSVersion::SYMBOLS.keys].include?(Homebrew::SimulateSystem.os)
+      end
 
-        sig { returns(Symbol) }
-        def current_os
-          Homebrew::SimulateSystem.os || ::MacOS.version.to_sym
-        end
+      sig { returns(Symbol) }
+      def current_os
+        Homebrew::SimulateSystem.os || MacOS.version.to_sym
       end
     end
   end
 end
 
-Homebrew::SimulateSystem.singleton_class.prepend(Homebrew::OS::MacOS::SimulateSystem)
+Homebrew::SimulateSystem.singleton_class.prepend(OS::Mac::SimulateSystem)
diff --git a/Library/Homebrew/formula_auditor.rb b/Library/Homebrew/formula_auditor.rb
index e3132f98e47ab..c19909e2f9199 100644
--- a/Library/Homebrew/formula_auditor.rb
+++ b/Library/Homebrew/formula_auditor.rb
@@ -504,9 +504,9 @@ def audit_glibc
       return unless @core_tap
       return if formula.name != "glibc"
       # Also allow LINUX_GLIBC_NEXT_CI_VERSION for when we're upgrading.
-      return if [::OS::LINUX_GLIBC_CI_VERSION, ::OS::LINUX_GLIBC_NEXT_CI_VERSION].include?(formula.version.to_s)
+      return if [OS::LINUX_GLIBC_CI_VERSION, OS::LINUX_GLIBC_NEXT_CI_VERSION].include?(formula.version.to_s)
 
-      problem "The glibc version must be #{::OS::LINUX_GLIBC_CI_VERSION}, as needed by our CI on Linux. " \
+      problem "The glibc version must be #{OS::LINUX_GLIBC_CI_VERSION}, as needed by our CI on Linux. " \
               "The glibc formula is for users who have a system glibc with a lower version, " \
               "which allows them to use our Linux bottles, which were compiled against system glibc on CI."
     end
diff --git a/Library/Homebrew/rubocops/move_to_extend_os.rb b/Library/Homebrew/rubocops/move_to_extend_os.rb
index 30457528e1976..00aa8742c661c 100644
--- a/Library/Homebrew/rubocops/move_to_extend_os.rb
+++ b/Library/Homebrew/rubocops/move_to_extend_os.rb
@@ -9,7 +9,7 @@ class MoveToExtendOS < Base
         MSG = "Move `OS.linux?` and `OS.mac?` calls to `extend/os`."
 
         def_node_matcher :os_check?, <<~PATTERN
-          (send (const {nil? cbase} :OS) {:mac? | :linux?})
+          (send (const nil? :OS) {:mac? | :linux?})
         PATTERN
 
         def on_send(node)
diff --git a/Library/Homebrew/test/rubocops/move_to_extend_os_spec.rb b/Library/Homebrew/test/rubocops/move_to_extend_os_spec.rb
index 5d1e434c2b4d1..a20b0d949e149 100644
--- a/Library/Homebrew/test/rubocops/move_to_extend_os_spec.rb
+++ b/Library/Homebrew/test/rubocops/move_to_extend_os_spec.rb
@@ -18,18 +18,4 @@
       ^^^^^^^ Homebrew/MoveToExtendOS: Move `OS.linux?` and `OS.mac?` calls to `extend/os`.
     RUBY
   end
-
-  it "registers an offense when using `::OS.linux?`" do
-    expect_offense(<<~RUBY)
-      ::OS.linux?
-      ^^^^^^^^^^^ Homebrew/MoveToExtendOS: Move `OS.linux?` and `OS.mac?` calls to `extend/os`.
-    RUBY
-  end
-
-  it "registers an offense when using `::OS.mac?`" do
-    expect_offense(<<~RUBY)
-      ::OS.mac?
-      ^^^^^^^^^ Homebrew/MoveToExtendOS: Move `OS.linux?` and `OS.mac?` calls to `extend/os`.
-    RUBY
-  end
 end