diff --git a/Library/Homebrew/cmd/audit.rb b/Library/Homebrew/cmd/audit.rb
index f3a97fdb4c..da07d207f2 100644
--- a/Library/Homebrew/cmd/audit.rb
+++ b/Library/Homebrew/cmd/audit.rb
@@ -770,6 +770,10 @@ class FormulaAuditor
       problem "Use MacOS.version instead of MACOS_VERSION"
     end
 
+    if line =~ /MACOS_FULL_VERSION/
+      problem "Use MacOS.full_version instead of MACOS_FULL_VERSION"
+    end
+
     cats = %w[leopard snow_leopard lion mountain_lion].join("|")
     if line =~ /MacOS\.(?:#{cats})\?/
       problem "\"#{$&}\" is deprecated, use a comparison to MacOS.version instead"
diff --git a/Library/Homebrew/cmd/config.rb b/Library/Homebrew/cmd/config.rb
index fb83951359..2281f644c9 100644
--- a/Library/Homebrew/cmd/config.rb
+++ b/Library/Homebrew/cmd/config.rb
@@ -145,7 +145,7 @@ module Homebrew
     f.puts "HOMEBREW_CELLAR: #{HOMEBREW_CELLAR}"
     f.puts "HOMEBREW_BOTTLE_DOMAIN: #{BottleSpecification::DEFAULT_DOMAIN}"
     f.puts hardware
-    f.puts "OS X: #{MACOS_FULL_VERSION}-#{kernel}"
+    f.puts "OS X: #{MacOS.full_version}-#{kernel}"
     f.puts "Xcode: #{xcode ? xcode : "N/A"}"
     f.puts "CLT: #{clt ? clt : "N/A"}"
     f.puts "GCC-4.0: build #{gcc_40}" if gcc_40
diff --git a/Library/Homebrew/cmd/gist-logs.rb b/Library/Homebrew/cmd/gist-logs.rb
index db89f8e2e7..495041a712 100644
--- a/Library/Homebrew/cmd/gist-logs.rb
+++ b/Library/Homebrew/cmd/gist-logs.rb
@@ -34,7 +34,7 @@ module Homebrew
         auth = :AUTH_BASIC
       end
 
-      url = new_issue(f.tap, "#{f.name} failed to build on #{MACOS_FULL_VERSION}", url, auth)
+      url = new_issue(f.tap, "#{f.name} failed to build on #{MacOS.full_version}", url, auth)
     end
 
     puts url if url
diff --git a/Library/Homebrew/global.rb b/Library/Homebrew/global.rb
index 4ab84941c3..277994476f 100644
--- a/Library/Homebrew/global.rb
+++ b/Library/Homebrew/global.rb
@@ -26,15 +26,6 @@ else
 end
 RUBY_BIN = RUBY_PATH.dirname
 
-if RUBY_PLATFORM =~ /darwin/
-  MACOS_FULL_VERSION = `/usr/bin/sw_vers -productVersion`.chomp
-  MACOS_VERSION = MACOS_FULL_VERSION[/10\.\d+/]
-  OS_VERSION = "OS X #{MACOS_FULL_VERSION}"
-else
-  MACOS_FULL_VERSION = MACOS_VERSION = "0"
-  OS_VERSION = RUBY_PLATFORM
-end
-
 HOMEBREW_GITHUB_API_TOKEN = ENV["HOMEBREW_GITHUB_API_TOKEN"]
 HOMEBREW_USER_AGENT = "Homebrew #{HOMEBREW_VERSION} (Ruby #{RUBY_VERSION}-#{RUBY_PATCHLEVEL}; #{OS_VERSION})"
 
diff --git a/Library/Homebrew/os.rb b/Library/Homebrew/os.rb
index 93df62b7d9..1b8ed7b8ec 100644
--- a/Library/Homebrew/os.rb
+++ b/Library/Homebrew/os.rb
@@ -8,11 +8,19 @@ module OS
   end
 
   if OS.mac?
+    require "os/mac"
     ISSUES_URL = "https://git.io/brew-troubleshooting"
     PATH_OPEN = "/usr/bin/open"
+    # compatibility
+    ::MACOS_FULL_VERSION = OS::Mac.full_version.to_s
+    ::MACOS_VERSION = OS::Mac.version.to_s
+    ::OS_VERSION = "OS X #{MACOS_FULL_VERSION}"
   elsif OS.linux?
     ISSUES_URL = "https://github.com/Homebrew/linuxbrew/wiki/troubleshooting"
     PATH_OPEN = "xdg-open"
+    # compatibility
+    ::MACOS_FULL_VERSION = ::MACOS_VERSION = "0"
+    ::OS_VERSION = RUBY_PLATFORM
   else
     raise "Unknown operating system"
   end
diff --git a/Library/Homebrew/os/mac.rb b/Library/Homebrew/os/mac.rb
index 2fda9c085d..691f92b519 100644
--- a/Library/Homebrew/os/mac.rb
+++ b/Library/Homebrew/os/mac.rb
@@ -12,7 +12,13 @@ module OS
     # This can be compared to numerics, strings, or symbols
     # using the standard Ruby Comparable methods.
     def version
-      @version ||= Version.new(MACOS_VERSION)
+      @version ||= Version.new(full_version.to_s[/10\.\d+/])
+    end
+
+    # This can be compared to numerics, strings, or symbols
+    # using the standard Ruby Comparable methods.
+    def full_version
+      @full_version ||= Version.new(`/usr/bin/sw_vers -productVersion`.chomp)
     end
 
     def cat