diff --git a/notebook/static/tree/js/notebooklist.js b/notebook/static/tree/js/notebooklist.js
index 8c2658134..7f196d740 100644
--- a/notebook/static/tree/js/notebooklist.js
+++ b/notebook/static/tree/js/notebooklist.js
@@ -155,11 +155,15 @@ define([
                 // descending order, then sort it on ascending order
                 if (!that.datetime_sorted || that.datetime_sorted == 2) {
                    that.sort_datetime(1);
+                    $("#button-last-modified i").removeClass("fa-arrow-down");
+                    $("#button-last-modified i").addClass("fa-arrow-up");
                    that.datetime_sorted = 1;
                 } else {
                     // Otherwise sort the list in descending order and set
                     // the value of datetime_sorted appropriately
                     that.sort_datetime(2);
+                    $("#button-last-modified i").removeClass("fa-arrow-up");
+                    $("#button-last-modified i").addClass("fa-arrow-down");
                     that.datetime_sorted = 2;
                 }
             });
diff --git a/notebook/templates/tree.html b/notebook/templates/tree.html
index 5553b575e..c442f1713 100644
--- a/notebook/templates/tree.html
+++ b/notebook/templates/tree.html
@@ -104,6 +104,7 @@ data-terminals-available="{{terminals_available}}"
               <div id="last_modified" class="pull-right">
                   <span class="btn btn-xs btn-default" id="button-last-modified">
                       Last Modified
+                      <i class="fa fa-arrow-up"></i>
                   </span>
               </div>
             </div>