diff --git a/Library/Homebrew/test/testing_env.rb b/Library/Homebrew/test/testing_env.rb
index 45d2f7d18b..f2a9fdce74 100644
--- a/Library/Homebrew/test/testing_env.rb
+++ b/Library/Homebrew/test/testing_env.rb
@@ -12,9 +12,13 @@ require 'extend/enumerable'
 require 'exceptions'
 require 'utils'
 require 'rbconfig'
+require 'tmpdir'
+
+tmpdir = Dir.mktmpdir
+at_exit { FileUtils.remove_entry(tmpdir) }
 
 # Constants normally defined in global.rb
-HOMEBREW_PREFIX        = Pathname.new('/private/tmp/testbrew/prefix')
+HOMEBREW_PREFIX        = Pathname.new(tmpdir).join("prefix")
 HOMEBREW_REPOSITORY    = HOMEBREW_PREFIX
 HOMEBREW_LIBRARY       = HOMEBREW_REPOSITORY+'Library'
 HOMEBREW_CACHE         = HOMEBREW_PREFIX.parent+'cache'
@@ -48,8 +52,6 @@ ORIGINAL_PATHS = ENV['PATH'].split(File::PATH_SEPARATOR).map{ |p| Pathname.new(p
   HOMEBREW_REPOSITORY.join(d).mkpath
 end
 
-at_exit { HOMEBREW_PREFIX.parent.rmtree }
-
 # Test fixtures and files can be found relative to this path
 TEST_DIRECTORY = File.dirname(File.expand_path(__FILE__))