diff --git modules/overlay/overlay-parent.js modules/overlay/overlay-parent.js
index 77f91cd..170498a 100644
--- modules/overlay/overlay-parent.js
+++ modules/overlay/overlay-parent.js
@@ -685,6 +685,7 @@ Drupal.overlay.clickHandler = function (event) {
   }
 
   var href = $target.attr('href');
+  var hostname = $target.get(0).hostname;
   // Only continue if link has an href attribute and is not just linking to
   // an anchor.
   if (href != undefined && href != '' && href.charAt(0) != '#') {
@@ -707,7 +708,7 @@ Drupal.overlay.clickHandler = function (event) {
       }
     }
     // Open external links in a new window.
-    else if ($target.get(0).hostname != window.location.hostname) {
+    else if (hostname !== window.location.hostname && hostname !== '') {
       // Add a target attribute to the clicked link. This is being picked up by
       // the default action handler.
       $target.attr('target', '_new');