diff --git a/lib/redmine_dmsf/webdav/download.rb b/lib/redmine_dmsf/webdav/download.rb
index 4a8c0dbf..4a2cb945 100644
--- a/lib/redmine_dmsf/webdav/download.rb
+++ b/lib/redmine_dmsf/webdav/download.rb
@@ -45,7 +45,7 @@ module RedmineDmsf
         if available
           serving(env)
         else
-          return fail(403, 'Not Found')          
+          fail(404, "File not found: #{@path}")
         end
       end
     end