diff --git a/test/rdoc/support/test_case.rb b/test/rdoc/support/test_case.rb
index 9a4f04b76e..bce480252f 100644
--- a/test/rdoc/support/test_case.rb
+++ b/test/rdoc/support/test_case.rb
@@ -49,6 +49,9 @@ class RDoc::TestCase < Test::Unit::TestCase
   def setup
     super
 
+    @orig_home = ENV["HOME"]
+    ENV["HOME"] = Dir.tmpdir
+
     @top_level = nil
 
     @RM = RDoc::Markup
@@ -69,6 +72,15 @@ class RDoc::TestCase < Test::Unit::TestCase
     RDoc::Markup::PreProcess.reset
   end
 
+  ##
+  # Abstract test-case teardown
+
+  def teardown
+    ENV["HOME"] = @orig_home
+
+    super
+  end
+
   ##
   # Asserts +path+ is a file