diff --git a/sphinx/themes/default/static/sidebar.js_t b/sphinx/themes/default/static/sidebar.js_t
index 242005254..2a1bd0d24 100644
--- a/sphinx/themes/default/static/sidebar.js_t
+++ b/sphinx/themes/default/static/sidebar.js_t
@@ -148,7 +148,7 @@ $(function() {
     var items = document.cookie.split(';');
     for(var k=0; k<items.length; k++) {
       var key_val = items[k].split('=');
-      var key = key_val[0];
+      var key = key_val[0].replace(/ /, "");  // strip leading spaces
       if (key == 'sidebar') {
         var value = key_val[1];
         if ((value == 'collapsed') && (!sidebar_is_collapsed()))