diff --git a/Library/Homebrew/test/testing_env.rb b/Library/Homebrew/test/testing_env.rb
index a975a83e14..dbd7b8cba0 100644
--- a/Library/Homebrew/test/testing_env.rb
+++ b/Library/Homebrew/test/testing_env.rb
@@ -17,6 +17,7 @@ require 'utils'
 # homebrew tree, and we do want to test everything :)
 HOMEBREW_PREFIX=Pathname.new '/private/tmp/testbrew/prefix'
 HOMEBREW_REPOSITORY=HOMEBREW_PREFIX
+HOMEBREW_LIBRARY=HOMEBREW_REPOSITORY+"Library"
 HOMEBREW_CACHE=HOMEBREW_PREFIX.parent+"cache"
 HOMEBREW_CACHE_FORMULA=HOMEBREW_PREFIX.parent+"formula_cache"
 HOMEBREW_CELLAR=HOMEBREW_PREFIX.parent+"cellar"