diff --git a/app/models/attachment.rb b/app/models/attachment.rb
index eea80132c..64ac2c2d1 100644
--- a/app/models/attachment.rb
+++ b/app/models/attachment.rb
@@ -156,7 +156,7 @@ class Attachment < ActiveRecord::Base
   end
 
   def title
-    title = filename.to_s
+    title = filename.dup
     if description.present?
       title << " (#{description})"
     end
diff --git a/test/unit/attachment_test.rb b/test/unit/attachment_test.rb
index e55c60b86..4093df75d 100644
--- a/test/unit/attachment_test.rb
+++ b/test/unit/attachment_test.rb
@@ -262,6 +262,7 @@ class AttachmentTest < ActiveSupport::TestCase
 
     a = Attachment.new(:filename => "test.png", :description => "Cool image")
     assert_equal "test.png (Cool image)", a.title
+    assert_equal "test.png", a.filename
   end
 
   def test_new_attachment_should_be_editable_by_author