diff --git a/Library/ENV/4.3/cc b/Library/ENV/4.3/cc
index 9172d3cea3..7a40d2e389 100755
--- a/Library/ENV/4.3/cc
+++ b/Library/ENV/4.3/cc
@@ -40,7 +40,7 @@ end
 
 class Cmd
   def initialize path, args
-    @arg0 = path.basename.freeze
+    @arg0 = File.basename(path).freeze
     @args = args.freeze
   end
   def mode
diff --git a/Library/ENV/4.3/xcrun b/Library/ENV/4.3/xcrun
index 16600e2403..6921bb3c47 100755
--- a/Library/ENV/4.3/xcrun
+++ b/Library/ENV/4.3/xcrun
@@ -4,19 +4,21 @@
 # But many build-systems expect it to work. This fixes that.
 # NOTE only works if the build-tool calls xcrun without a path prefixed!
 
-require "#{File.dirname __FILE__}/../libsuperenv"
-SUPERBIN = __FILE__.dirname.cleanpath.freeze
+dirname = File.dirname(__FILE__)
+require "#{dirname}/../libsuperenv"
+SUPERBIN = dirname.cleanpath.freeze
 
 # Some build tools are stupid and still set DEVELOPER_DIR to old /Developer
 ENV['DEVELOPER_DIR'] = ENV['HOMEBREW_DEVELOPER_DIR']
 
 exec "/usr/bin/xcrun", *ARGV if ARGV.empty? or ARGV[0][0..0] == '-'
 if File.exist?("/usr/bin/#{ARGV.first}")
-  exec "/usr/bin/#{ARGV.shift}", *ARGV unless ENV['HOMEBREW_SDKROOT'].directory?
+  sdkroot = ENV['HOMEBREW_SDKROOT']
+  exec "/usr/bin/#{ARGV.shift}", *ARGV unless sdkroot and File.directory? sdkroot
 end
 
 def try path
-  exec path, *ARGV if File.executable?(path) and path.cleanpath.dirname != SUPERBIN
+  exec path, *ARGV if File.executable?(path) and File.dirname(path.cleanpath) != SUPERBIN
 end
 
 arg0 = ARGV.shift
diff --git a/Library/ENV/libsuperenv.rb b/Library/ENV/libsuperenv.rb
index e08fbba4da..c87e6a4996 100644
--- a/Library/ENV/libsuperenv.rb
+++ b/Library/ENV/libsuperenv.rb
@@ -6,22 +6,18 @@
 $:.unshift "/System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/1.8"
 
 class String
-  def directory?; File.directory? self end
-  def basename; File.basename self end
   def cleanpath; require 'pathname'; Pathname.new(self).realpath.to_s rescue self end
   def chuzzle; s = chomp; s unless s.empty? end
-  def dirname; File.dirname(self) end
 end
 
 class NilClass
   def chuzzle; end
-  def directory?; false end
   def split(x); [] end
 end
 
 class Array
   def to_flags prefix
-    select{|path| path.directory? }.uniq.map{|path| prefix+path }
+    select { |path| File.directory? path }.uniq.map { |path| prefix + path }
   end
 end