diff --git a/test/fakefs_test.rb b/test/fakefs_test.rb
index a0863a4..67ab301 100644
--- a/test/fakefs_test.rb
+++ b/test/fakefs_test.rb
@@ -4,9 +4,14 @@ class FakeFSTest < Test::Unit::TestCase
   include FakeFS
 
   def setup
+    FakeFS.activate!
     FileSystem.clear
   end
 
+  def teardown
+    FakeFS.deactivate!
+  end
+
   def test_can_be_initialized_empty
     fs = FileSystem
     assert_equal 0, fs.files.size
diff --git a/test/safe_test.rb b/test/safe_test.rb
index 9db2de0..f16dc4e 100644
--- a/test/safe_test.rb
+++ b/test/safe_test.rb
@@ -5,6 +5,10 @@ class FakeFSSafeTest < Test::Unit::TestCase
     FakeFS.deactivate!
   end
 
+  def teardown
+    FakeFS.activate!
+  end
+
   def test_FakeFS_method_does_not_intrude_on_global_namespace
     path = '/path/to/file.txt'