diff --git a/Library/Homebrew/test/lib/config.rb b/Library/Homebrew/test/lib/config.rb
index 86b652660d..adf150c2e9 100644
--- a/Library/Homebrew/test/lib/config.rb
+++ b/Library/Homebrew/test/lib/config.rb
@@ -1,7 +1,9 @@
 require "tmpdir"
 
+HOMEBREW_TEMP = Pathname.new(ENV["HOMEBREW_TEMP"] || "/tmp")
+
 TEST_TMPDIR = ENV.fetch("HOMEBREW_TEST_TMPDIR") { |k|
-  dir = Dir.mktmpdir("homebrew_tests")
+  dir = Dir.mktmpdir("homebrew_tests", HOMEBREW_TEMP)
   at_exit { FileUtils.remove_entry(dir) }
   ENV[k] = dir
 }
@@ -13,4 +15,3 @@ HOMEBREW_CACHE         = HOMEBREW_PREFIX.parent+"cache"
 HOMEBREW_CACHE_FORMULA = HOMEBREW_PREFIX.parent+"formula_cache"
 HOMEBREW_CELLAR        = HOMEBREW_PREFIX.parent+"cellar"
 HOMEBREW_LOGS          = HOMEBREW_PREFIX.parent+"logs"
-HOMEBREW_TEMP          = Pathname.new(ENV["HOMEBREW_TEMP"] || "/tmp")
diff --git a/Library/Homebrew/test/test_pathname.rb b/Library/Homebrew/test/test_pathname.rb
index 3db0159673..caf650b5f7 100644
--- a/Library/Homebrew/test/test_pathname.rb
+++ b/Library/Homebrew/test/test_pathname.rb
@@ -7,8 +7,8 @@ module PathnameTestExtension
   include FileUtils
 
   def setup
-    @src  = Pathname.new(Dir.mktmpdir)
-    @dst  = Pathname.new(Dir.mktmpdir)
+    @src  = Pathname.new(mktmpdir)
+    @dst  = Pathname.new(mktmpdir)
     @file = @src+'foo'
     @dir  = @src+'bar'
   end
diff --git a/Library/Homebrew/test/test_sandbox.rb b/Library/Homebrew/test/test_sandbox.rb
index 0e76d0b8c3..2cf9c51063 100644
--- a/Library/Homebrew/test/test_sandbox.rb
+++ b/Library/Homebrew/test/test_sandbox.rb
@@ -5,7 +5,7 @@ class SandboxTest < Homebrew::TestCase
   def setup
     skip "sandbox not implemented" unless Sandbox.available?
     @sandbox = Sandbox.new
-    @dir = Pathname.new(Dir.mktmpdir)
+    @dir = Pathname.new(mktmpdir)
     @file = @dir/"foo"
   end
 
diff --git a/Library/Homebrew/test/testing_env.rb b/Library/Homebrew/test/testing_env.rb
index 0e58afeeaa..d9a0329b4a 100644
--- a/Library/Homebrew/test/testing_env.rb
+++ b/Library/Homebrew/test/testing_env.rb
@@ -91,6 +91,10 @@ module Homebrew
       end
     end
 
+    def mktmpdir(prefix_suffix=nil, &block)
+      Dir.mktmpdir(prefix_suffix, HOMEBREW_TEMP, &block)
+    end
+
     def assert_nothing_raised
       yield
     end