I'm creating documents with markdown which include reference links to external PDF documents which exist in the same folder. When I use pandoc to generate a PDF document from my markdown, there appear to be links in the PDF when I hover over the labels but the external PDF does not open when I click the link. I don't get any warnings of skipped files. Here's an example of my markdown reference, it's in a numbered list. 

 [ats alert tables](ats-alert-database-diagram.pdf)

I have read that pandoc references relative file paths according to the directory where pandoc is executed but I'm running pandoc in the directory containing the external PDF so I shouldn't have to add further pathing information should I? I'm also using Harp JS to create a static site from my content and the link references work in Harp so I don't want to change that to support pandoc. Ideally the relative paths should for both pandoc and Harp.

Any suggestions?