diff --git a/web/ui_utils.js b/web/ui_utils.js
index fd925d1ba..6e9cc9d30 100644
--- a/web/ui_utils.js
+++ b/web/ui_utils.js
@@ -371,8 +371,8 @@ function noContextMenuHandler(e) {
  * @return {String} Guessed PDF file name.
  */
 function getPDFFileNameFromURL(url) {
-  var reURI = /^(?:([^:]+:)?\/\/[^\/]+)?([^?#]*)(\?[^#]*)?(#.*)?$/;
-  //            SCHEME      HOST         1.PATH  2.QUERY   3.REF
+  var reURI = /^(?:(?:[^:]+:)?\/\/[^\/]+)?([^?#]*)(\?[^#]*)?(#.*)?$/;
+  //            SCHEME        HOST         1.PATH  2.QUERY   3.REF
   // Pattern to get last matching NAME.pdf
   var reFilename = /[^\/?#=]+\.pdf\b(?!.*\.pdf\b)/i;
   var splitURI = reURI.exec(url);