diff --git a/lib/autotest/rails.rb b/lib/autotest/rails.rb
index 3dda8a0..1e25783 100644
--- a/lib/autotest/rails.rb
+++ b/lib/autotest/rails.rb
@@ -80,7 +80,7 @@ def path_to_classname(s)
     sep = File::SEPARATOR
     parts = s.sub(/^test#{sep}((#{ignored_namespaces})#{sep})?/, '').sub(/\.rb$/, '').split(sep)
     modules = parts.map { |path| path.split(/_/).map { |seg| seg.capitalize }.join }
-    modules = modules.map { |path| path =~ /Test$/ ? path : "#{path}Test"  }
+    modules[-1] = "#{modules.last}Test" unless modules.last =~ /Test$/
     modules.join('::')
   end
 end
diff --git a/test/rails_test.rb b/test/rails_test.rb
index a9ef590..c603013 100644
--- a/test/rails_test.rb
+++ b/test/rails_test.rb
@@ -15,11 +15,15 @@ class RailsTest < MiniTest::Unit::TestCase
       end
 
       it "should convert non-default namespaces" do
-        assert_equal "FooTest::PostControllerTest", @at.path_to_classname("test/foo/post_controller_test.rb")
+        assert_equal "Foo::PostControllerTest", @at.path_to_classname("test/foo/post_controller_test.rb")
       end
 
       it "should convert normal namespaces inside ignored namespaces" do
-        assert_equal "BloggingTest::PostControllerTest", @at.path_to_classname("test/controllers/blogging/post_controller_test.rb")
+        assert_equal "Blogging::PostControllerTest", @at.path_to_classname("test/controllers/blogging/post_controller_test.rb")
+      end
+
+      it "does not remove _test namespces" do
+        assert_equal "BloggingTest::PostControllerTest", @at.path_to_classname("test/controllers/blogging_test/post_controller_test.rb")
       end
     end
   end