Set MACOS_VERSION as 0 on non-OSX platforms.

1 files changed, 2 insertions, 2 deletions

diff --git a/bin/brew b/bin/brew
index ba573c658..df0c45d4f 100755
--- a/bin/brew
+++ b/bin/brew
@@ -31,7 +31,7 @@ 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 MACOS_VERSION < 10.5
+if MACOS and MACOS_VERSION < 10.5
   abort <<-EOABORT.undent
     Homebrew requires Leopard or higher. For Tiger support, see:
     http://github.com/sceaga/homebrew/tree/tiger
@@ -72,7 +72,7 @@ begin
 
   # Add example external commands to PATH before checking.
   ENV['PATH'] += ":#{HOMEBREW_REPOSITORY}/Library/Contributions/cmds"
-  if system "/usr/bin/which -s brew-#{cmd}"
+  if which_s "brew-#{cmd}"
     %w[CACHE CELLAR LIBRARY_PATH PREFIX REPOSITORY].each do |e|
       ENV["HOMEBREW_#{e}"] = Object.const_get "HOMEBREW_#{e}"
     end