diff --git a/spec/lib/puppet_spec/files.rb b/spec/lib/puppet_spec/files.rb
index 9e75d3142..725bf2af9 100755
--- a/spec/lib/puppet_spec/files.rb
+++ b/spec/lib/puppet_spec/files.rb
@@ -1,63 +1,61 @@
 require 'fileutils'
 require 'tempfile'
+require 'pathname'
 
 # A support module for testing files.
 module PuppetSpec::Files
   # This code exists only to support tests that run as root, pretty much.
   # Once they have finally been eliminated this can all go... --daniel 2011-04-08
-  if Puppet.features.posix? then
-    def self.in_tmp(path)
-      path =~ /^\/tmp/ or path =~ /^\/var\/folders/
-    end
-  elsif Puppet.features.microsoft_windows?
-    def self.in_tmp(path)
-      tempdir = File.expand_path(File.join(Dir::LOCAL_APPDATA, "Temp"))
-      path =~ /^#{tempdir}/
+  def self.in_tmp(path)
+    tempdir = Dir.tmpdir
+
+    Pathname.new(path).ascend do |dir|
+      return true if File.identical?(tempdir, dir)
     end
-  else
-    fail "Help! Can't find in_tmp for this platform"
+
+    false
   end
 
   def self.cleanup
     $global_tempfiles ||= []
     while path = $global_tempfiles.pop do
       fail "Not deleting tmpfile #{path} outside regular tmpdir" unless in_tmp(path)
 
       begin
         FileUtils.rm_r path, :secure => true
       rescue Errno::ENOENT
         # nothing to do
       end
     end
   end
 
   def make_absolute(path)
     return path unless Puppet.features.microsoft_windows?
     # REMIND UNC
     return path if path =~ /^[A-Za-z]:/
 
     pwd = Dir.getwd
     return "#{pwd[0,2]}#{path}" if pwd.length > 2 and pwd =~ /^[A-Za-z]:/
     return "C:#{path}"
   end
 
   def tmpfile(name)
     # Generate a temporary file, just for the name...
     source = Tempfile.new(name)
     path = source.path
     source.close!
 
     # ...record it for cleanup,
     $global_tempfiles ||= []
     $global_tempfiles << File.expand_path(path)
 
     # ...and bam.
     path
   end
 
   def tmpdir(name)
     path = tmpfile(name)
     FileUtils.mkdir_p(path)
     path
   end
 end