diff --git a/Library/Homebrew/cmd/doctor.rb b/Library/Homebrew/cmd/doctor.rb
index 69d8039ad6..059e6f2840 100644
--- a/Library/Homebrew/cmd/doctor.rb
+++ b/Library/Homebrew/cmd/doctor.rb
@@ -193,7 +193,7 @@ end
 def check_xcode_clt
   if MacOS::Xcode.installed?
     __check_xcode_up_to_date
-  elsif MacOS.version >= 10.7
+  elsif MacOS.version >= "10.7"
     __check_clt_up_to_date
   else <<-EOS.undent
     Xcode not installed
@@ -225,7 +225,7 @@ def __check_clt_up_to_date
 end
 
 def check_for_osx_gcc_installer
-  if (MacOS.version < 10.7 || MacOS::Xcode.version < "4.1") && \
+  if (MacOS.version < "10.7" || MacOS::Xcode.version < "4.1") && \
     MacOS.clang_version == "2.1" then <<-EOS.undent
     You have osx-gcc-installer installed.
     Homebrew doesn't support osx-gcc-installer, and it is known to cause
diff --git a/Library/Homebrew/compat/macos.rb b/Library/Homebrew/compat/macos.rb
index 636807d484..d097a59459 100644
--- a/Library/Homebrew/compat/macos.rb
+++ b/Library/Homebrew/compat/macos.rb
@@ -33,21 +33,21 @@ module OS
     end
 
     def leopard?
-      version == 10.5
+      version == "10.5"
     end
 
     def snow_leopard?
-      version >= 10.6
+      version >= "10.6"
     end
     alias_method :snow_leopard_or_newer?, :snow_leopard?
 
     def lion?
-      version >= 10.7
+      version >= "10.7"
     end
     alias_method :lion_or_newer?, :lion?
 
     def mountain_lion?
-      version >= 10.8
+      version >= "10.8"
     end
     alias_method :mountain_lion_or_newer?, :mountain_lion?
 
diff --git a/Library/Homebrew/os/mac/xcode.rb b/Library/Homebrew/os/mac/xcode.rb
index 6820aa53a5..0a4a9a8fbc 100644
--- a/Library/Homebrew/os/mac/xcode.rb
+++ b/Library/Homebrew/os/mac/xcode.rb
@@ -30,7 +30,7 @@ module OS
         when "10.9"         then "5.0.1"
         else
           # Default to newest known version of Xcode for unreleased OSX versions.
-          if MacOS.version > 10.9
+          if MacOS.version > "10.9"
             "5.0.1"
           else
             raise "Mac OS X '#{MacOS.version}' is invalid"
diff --git a/Library/Homebrew/utils.rb b/Library/Homebrew/utils.rb
index ca9aad542f..f3ac5e447c 100644
--- a/Library/Homebrew/utils.rb
+++ b/Library/Homebrew/utils.rb
@@ -138,7 +138,7 @@ def curl *args
 
   args = [HOMEBREW_CURL_ARGS, HOMEBREW_USER_AGENT, *args]
   # See https://github.com/mxcl/homebrew/issues/6103
-  args << "--insecure" if MacOS.version < 10.6
+  args << "--insecure" if MacOS.version < "10.6"
   args << "--verbose" if ENV['HOMEBREW_CURL_VERBOSE']
   args << "--silent" unless $stdout.tty?
 
diff --git a/Library/brew.rb b/Library/brew.rb
index b72d61494f..0c1aef8126 100755
--- a/Library/brew.rb
+++ b/Library/brew.rb
@@ -35,7 +35,7 @@ case HOMEBREW_PREFIX.to_s when '/', '/usr'
   # it may work, but I only see pain this route and don't want to support it
   abort "Cowardly refusing to continue at this prefix: #{HOMEBREW_PREFIX}"
 end
-if OS.mac? and MacOS.version < 10.5
+if OS.mac? and MacOS.version < "10.5"
   abort <<-EOABORT.undent
     Homebrew requires Leopard or higher. For Tiger support, see:
     https://github.com/mistydemeo/tigerbrew