diff --git a/lisp/org/org.el b/lisp/org/org.el
index cc4c93f..285b71c 100644
--- a/lisp/org/org.el
+++ b/lisp/org/org.el
@@ -1750,7 +1750,7 @@ See `org-file-apps'.")
     (auto-mode . emacs)
     ("\\.mm\\'" . default)
     ("\\.x?html?\\'" . default)
-    ("\\.pdf\\'" . default)
+    ("\\.pdf\\'" . xdg-open)
     )
   "External applications for opening `file:path' items in a document.
 Org-mode uses system defaults for different file types, but