diff --git a/Library/Homebrew/compat/ENV/shared.rb b/Library/Homebrew/compat/ENV/shared.rb
index 6bca25f9de..4e8cd32918 100644
--- a/Library/Homebrew/compat/ENV/shared.rb
+++ b/Library/Homebrew/compat/ENV/shared.rb
@@ -1,9 +1,13 @@
 module SharedEnvExtension
-  def j1
-    odisabled "ENV.j1", "ENV.deparallelize"
+  module Compat
+    def j1
+      odisabled "ENV.j1", "ENV.deparallelize"
+    end
+
+    def java_cache
+      odisabled "ENV.java_cache"
+    end
   end
 
-  def java_cache
-    odisabled "ENV.java_cache"
-  end
+  prepend Compat
 end
diff --git a/Library/Homebrew/compat/dependable.rb b/Library/Homebrew/compat/dependable.rb
index 1b7eec2f0c..583bf51dab 100644
--- a/Library/Homebrew/compat/dependable.rb
+++ b/Library/Homebrew/compat/dependable.rb
@@ -1,6 +1,10 @@
 module Dependable
-  def run?
-    odeprecated "Dependable#run?"
-    tags.include? :run
+  module Compat
+    def run?
+      odeprecated "Dependable#run?"
+      tags.include? :run
+    end
   end
+
+  prepend Compat
 end
diff --git a/Library/Homebrew/compat/extend/string.rb b/Library/Homebrew/compat/extend/string.rb
index b704cd2b5f..3155168149 100644
--- a/Library/Homebrew/compat/extend/string.rb
+++ b/Library/Homebrew/compat/extend/string.rb
@@ -1,19 +1,23 @@
 class String
-  def undent
-    odisabled "<<-EOS.undent", "<<~EOS"
-    self
-  end
-  alias unindent undent
+  module Compat
+    def undent
+      odisabled "<<-EOS.undent", "<<~EOS"
+      self
+    end
+    alias unindent undent
 
-  # eg:
-  #   if foo then <<-EOS.undent_________________________________________________________72
-  #               Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do
-  #               eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad
-  #               minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip
-  #               ex ea commodo consequat. Duis aute irure dolor in reprehenderit in
-  #               voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur
-  #               sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt
-  #               mollit anim id est laborum.
-  #               EOS
-  alias undent_________________________________________________________72 undent
+    # eg:
+    #   if foo then <<-EOS.undent_________________________________________________________72
+    #               Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do
+    #               eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad
+    #               minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip
+    #               ex ea commodo consequat. Duis aute irure dolor in reprehenderit in
+    #               voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur
+    #               sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt
+    #               mollit anim id est laborum.
+    #               EOS
+    alias undent_________________________________________________________72 undent
+  end
+
+  prepend Compat
 end
diff --git a/Library/Homebrew/compat/formula.rb b/Library/Homebrew/compat/formula.rb
index 397b8e12ca..7432865f12 100644
--- a/Library/Homebrew/compat/formula.rb
+++ b/Library/Homebrew/compat/formula.rb
@@ -1,5 +1,9 @@
 class Formula
-  def rake(*)
-    odisabled "FileUtils#rake", "system \"rake\""
+  module Compat
+    def rake(*)
+      odisabled "FileUtils#rake", "system \"rake\""
+    end
   end
+
+  prepend Compat
 end
diff --git a/Library/Homebrew/compat/gpg.rb b/Library/Homebrew/compat/gpg.rb
index 5aaecf4d31..ef2bec4028 100644
--- a/Library/Homebrew/compat/gpg.rb
+++ b/Library/Homebrew/compat/gpg.rb
@@ -1,24 +1,27 @@
-
 module Gpg
-  module_function
+  class << self
+    module Compat
+      def executable
+        odisabled "Gpg.executable", 'which "gpg"'
+      end
 
-  def executable
-    odisabled "Gpg.executable", 'which "gpg"'
-  end
+      def available?
+        odisabled "Gpg.available?", 'which "gpg"'
+      end
 
-  def available?
-    odisabled "Gpg.available?", 'which "gpg"'
-  end
+      def create_test_key(*)
+        odisabled "Gpg.create_test_key"
+      end
 
-  def create_test_key(_)
-    odisabled "Gpg.create_test_key"
-  end
+      def cleanup_test_processes!
+        odisabled "Gpg.cleanup_test_processes!"
+      end
 
-  def cleanup_test_processes!
-    odisabled "Gpg.cleanup_test_processes!"
-  end
+      def test(*)
+        odisabled "Gpg.test"
+      end
+    end
 
-  def test(_)
-    odisabled "Gpg.test"
+    prepend Compat
   end
 end
diff --git a/Library/Homebrew/compat/hbc.rb b/Library/Homebrew/compat/hbc.rb
index 608d46e376..b64c3e4377 100644
--- a/Library/Homebrew/compat/hbc.rb
+++ b/Library/Homebrew/compat/hbc.rb
@@ -7,17 +7,17 @@ require "compat/hbc/dsl"
 
 module Hbc
   class << self
-    prepend(
-      Module.new do
-        def init
-          Cache.delete_legacy_cache
+    module Compat
+      def init
+        Cache.delete_legacy_cache
 
-          Caskroom.migrate_caskroom_from_repo_to_prefix
-          Caskroom.migrate_legacy_caskroom
+        Caskroom.migrate_caskroom_from_repo_to_prefix
+        Caskroom.migrate_legacy_caskroom
 
-          super
-        end
-      end,
-    )
+        super
+      end
+    end
+
+    prepend Compat
   end
 end
diff --git a/Library/Homebrew/compat/hbc/cache.rb b/Library/Homebrew/compat/hbc/cache.rb
index 34221fcf1d..68b6d4f869 100644
--- a/Library/Homebrew/compat/hbc/cache.rb
+++ b/Library/Homebrew/compat/hbc/cache.rb
@@ -1,13 +1,17 @@
 module Hbc
   module Cache
-    module_function
+    class << self
+      module Compat
+        def delete_legacy_cache
+          legacy_cache = HOMEBREW_CACHE.join("Casks")
+          return unless legacy_cache.exist?
 
-    def delete_legacy_cache
-      legacy_cache = HOMEBREW_CACHE.join("Casks")
-      return unless legacy_cache.exist?
+          ohai "Deleting legacy cache at #{legacy_cache}"
+          FileUtils.remove_entry_secure(legacy_cache)
+        end
+      end
 
-      ohai "Deleting legacy cache at #{legacy_cache}"
-      FileUtils.remove_entry_secure(legacy_cache)
+      prepend Compat
     end
   end
 end
diff --git a/Library/Homebrew/compat/hbc/cask_loader.rb b/Library/Homebrew/compat/hbc/cask_loader.rb
index e57aea71dd..c62c001a2f 100644
--- a/Library/Homebrew/compat/hbc/cask_loader.rb
+++ b/Library/Homebrew/compat/hbc/cask_loader.rb
@@ -1,22 +1,22 @@
-module CaskLoaderCompatibilityLayer
-  private
-
-  def cask(header_token, **options, &block)
-    if header_token.is_a?(Hash) && header_token.key?(:v1)
-      odeprecated %q("cask :v1 => 'token'"), %q("cask 'token'")
-      header_token = header_token[:v1]
-    end
-
-    super(header_token, **options, &block)
-  end
-end
-
 module Hbc
   module CaskLoader
     class FromContentLoader; end
 
     class FromPathLoader < FromContentLoader
-      prepend CaskLoaderCompatibilityLayer
+      module Compat
+        private
+
+        def cask(header_token, **options, &block)
+          if header_token.is_a?(Hash) && header_token.key?(:v1)
+            odeprecated %q("cask :v1 => 'token'"), %q("cask 'token'")
+            header_token = header_token[:v1]
+          end
+
+          super(header_token, **options, &block)
+        end
+      end
+
+      prepend Compat
     end
   end
 end
diff --git a/Library/Homebrew/compat/hbc/caskroom.rb b/Library/Homebrew/compat/hbc/caskroom.rb
index 3621a35fb0..2a1d9bf48f 100644
--- a/Library/Homebrew/compat/hbc/caskroom.rb
+++ b/Library/Homebrew/compat/hbc/caskroom.rb
@@ -1,45 +1,49 @@
 module Hbc
   module Caskroom
-    module_function
+    class << self
+      module Compat
+        def migrate_legacy_caskroom
+          return if Hbc.caskroom.exist?
 
-    def migrate_legacy_caskroom
-      return if Hbc.caskroom.exist?
+          legacy_caskroom = Pathname.new("/opt/homebrew-cask/Caskroom")
+          return if Hbc.caskroom == legacy_caskroom
+          return unless legacy_caskroom.exist?
+          return if legacy_caskroom.symlink?
 
-      legacy_caskroom = Pathname.new("/opt/homebrew-cask/Caskroom")
-      return if Hbc.caskroom == legacy_caskroom
-      return unless legacy_caskroom.exist?
-      return if legacy_caskroom.symlink?
+          ohai "Migrating Caskroom from #{legacy_caskroom} to #{Hbc.caskroom}."
+          if Hbc.caskroom.parent.writable?
+            FileUtils.mv legacy_caskroom, Hbc.caskroom
+          else
+            opoo "#{Hbc.caskroom.parent} is not writable, sudo is needed to move the Caskroom."
+            SystemCommand.run("/bin/mv", args: [legacy_caskroom, Hbc.caskroom.parent], sudo: true)
+          end
 
-      ohai "Migrating Caskroom from #{legacy_caskroom} to #{Hbc.caskroom}."
-      if Hbc.caskroom.parent.writable?
-        FileUtils.mv legacy_caskroom, Hbc.caskroom
-      else
-        opoo "#{Hbc.caskroom.parent} is not writable, sudo is needed to move the Caskroom."
-        SystemCommand.run("/bin/mv", args: [legacy_caskroom, Hbc.caskroom.parent], sudo: true)
+          ohai "Creating symlink from #{Hbc.caskroom} to #{legacy_caskroom}."
+          if legacy_caskroom.parent.writable?
+            FileUtils.ln_s Hbc.caskroom, legacy_caskroom
+          else
+            opoo "#{legacy_caskroom.parent} is not writable, sudo is needed to link the Caskroom."
+            SystemCommand.run("/bin/ln", args: ["-s", Hbc.caskroom, legacy_caskroom], sudo: true)
+          end
+        end
+
+        def migrate_caskroom_from_repo_to_prefix
+          repo_caskroom = HOMEBREW_REPOSITORY.join("Caskroom")
+          return if Hbc.caskroom.exist?
+          return unless repo_caskroom.directory?
+
+          ohai "Moving Caskroom from HOMEBREW_REPOSITORY to HOMEBREW_PREFIX"
+
+          if Hbc.caskroom.parent.writable?
+            FileUtils.mv repo_caskroom, Hbc.caskroom
+          else
+            opoo "#{Hbc.caskroom.parent} is not writable, sudo is needed to move the Caskroom."
+            SystemCommand.run("/bin/mv", args: [repo_caskroom, Hbc.caskroom.parent], sudo: true)
+          end
+        end
       end
 
-      ohai "Creating symlink from #{Hbc.caskroom} to #{legacy_caskroom}."
-      if legacy_caskroom.parent.writable?
-        FileUtils.ln_s Hbc.caskroom, legacy_caskroom
-      else
-        opoo "#{legacy_caskroom.parent} is not writable, sudo is needed to link the Caskroom."
-        SystemCommand.run("/bin/ln", args: ["-s", Hbc.caskroom, legacy_caskroom], sudo: true)
-      end
-    end
-
-    def migrate_caskroom_from_repo_to_prefix
-      repo_caskroom = HOMEBREW_REPOSITORY.join("Caskroom")
-      return if Hbc.caskroom.exist?
-      return unless repo_caskroom.directory?
-
-      ohai "Moving Caskroom from HOMEBREW_REPOSITORY to HOMEBREW_PREFIX"
-
-      if Hbc.caskroom.parent.writable?
-        FileUtils.mv repo_caskroom, Hbc.caskroom
-      else
-        opoo "#{Hbc.caskroom.parent} is not writable, sudo is needed to move the Caskroom."
-        SystemCommand.run("/bin/mv", args: [repo_caskroom, Hbc.caskroom.parent], sudo: true)
-      end
+      prepend Compat
     end
   end
 end
diff --git a/Library/Homebrew/compat/hbc/cli/update.rb b/Library/Homebrew/compat/hbc/cli/update.rb
index 95321e8981..348e3a2c76 100644
--- a/Library/Homebrew/compat/hbc/cli/update.rb
+++ b/Library/Homebrew/compat/hbc/cli/update.rb
@@ -2,22 +2,18 @@ require "cask/lib/hbc/cli/abstract_command"
 
 module Hbc
   class CLI
-    class Update < AbstractCommand
-      def self.run(*_ignored)
-        odeprecated "`brew cask update`", "`brew update`", disable_on: Time.utc(2017, 7, 1)
-        result = SystemCommand.run(HOMEBREW_BREW_FILE, args:         ["update"],
-                                                       print_stderr: true,
-                                                       print_stdout: true)
-        exit result.exit_status
-      end
+    module Compat
+      class Update < AbstractCommand
+        def self.run(*_ignored)
+          odisabled "`brew cask update`", "`brew update`"
+        end
 
-      def self.visible
-        false
-      end
-
-      def self.help
-        "a synonym for 'brew update'"
+        def self.visible
+          false
+        end
       end
     end
+
+    prepend Compat
   end
 end
diff --git a/Library/Homebrew/compat/hbc/dsl.rb b/Library/Homebrew/compat/hbc/dsl.rb
index b550501ed5..483ca4a7e6 100644
--- a/Library/Homebrew/compat/hbc/dsl.rb
+++ b/Library/Homebrew/compat/hbc/dsl.rb
@@ -1,7 +1,11 @@
 module Hbc
   class DSL
-    def license(*)
-      odeprecated "Hbc::DSL#license"
+    module Compat
+      def license(*)
+        odeprecated "Hbc::DSL#license"
+      end
     end
+
+    prepend Compat
   end
 end
diff --git a/Library/Homebrew/compat/os/mac.rb b/Library/Homebrew/compat/os/mac.rb
index 6806fe900a..a839399c2e 100644
--- a/Library/Homebrew/compat/os/mac.rb
+++ b/Library/Homebrew/compat/os/mac.rb
@@ -1,10 +1,14 @@
 module OS
   module Mac
     class << self
-      def release
-        odeprecated "MacOS.release", "MacOS.version"
-        version
+      module Compat
+        def release
+          odeprecated "MacOS.release", "MacOS.version"
+          version
+        end
       end
+
+      prepend Compat
     end
   end
 end
diff --git a/Library/Homebrew/test/cask/cli_spec.rb b/Library/Homebrew/test/cask/cli_spec.rb
index e88b24ba2a..495aedb088 100644
--- a/Library/Homebrew/test/cask/cli_spec.rb
+++ b/Library/Homebrew/test/cask/cli_spec.rb
@@ -74,8 +74,8 @@ describe Hbc::CLI, :cask do
     end
   end
 
-  it "provides a help message for all commands" do
-    described_class.command_classes.each do |command_class|
+  it "provides a help message for all visible commands" do
+    described_class.command_classes.select(&:visible).each do |command_class|
       expect(command_class.help).to match(/\w+/), command_class.name
     end
   end