diff --git a/lib/technoweenie/attachment_fu/backends/file_system_backend.rb b/lib/technoweenie/attachment_fu/backends/file_system_backend.rb
index 49cea643..160d3956 100644
--- a/lib/technoweenie/attachment_fu/backends/file_system_backend.rb
+++ b/lib/technoweenie/attachment_fu/backends/file_system_backend.rb
@@ -25,7 +25,7 @@ def full_filename(thumbnail = nil)
       
         # Used as the base path that #public_filename strips off full_filename to create the public path
         def base_path
-          @base_path ||= Rails.root.join('public')
+          @base_path ||= Rails.root.join('public').to_s
         end
       
         # The attachment ID used in the full path of a file