diff --git a/Library/Homebrew/unittest.rb b/Library/Homebrew/unittest.rb
index f1942434b6..6ad8b945c6 100755
--- a/Library/Homebrew/unittest.rb
+++ b/Library/Homebrew/unittest.rb
@@ -9,9 +9,9 @@ require 'utils'
 # these are defined in env.rb usually, but we don't want to break our actual
 # homebrew tree, and we do want to test everything :)
 HOMEBREW_VERSION='0.3t'
-HOMEBREW_CACHE=Pathname.new "/tmp/testbrew"
-HOMEBREW_PREFIX=Pathname.new(HOMEBREW_CACHE)+'prefix'
-HOMEBREW_CELLAR=Pathname.new(HOMEBREW_CACHE)+'cellar'
+HOMEBREW_PREFIX=Pathname.new '/tmp/testbrew/prefix'
+HOMEBREW_CACHE=HOMEBREW_PREFIX.parent+"cache"
+HOMEBREW_CELLAR=HOMEBREW_PREFIX.parent+"cellar"
 
 HOMEBREW_CELLAR.mkpath
 raise "HOMEBREW_CELLAR couldn't be created!" unless HOMEBREW_CELLAR.directory?