prob linking to static page in public folder

For the first time, I'm trying to link to a static page and running
into a problem...

Here's the link_to code:

<%= link_to "Terms of Service", '/terms_of_service.pdf', :popup =>
true %>

And here's the error I'm getting:

no route found to match "/terms_of_service.pdf" with {:method=>:get}

Should be simple and everything I've found says to do it this way...
but, I must be missing something or doing it wrong. Any ideas?