diff --git a/lib/ajax/section_classes.js b/lib/ajax/section_classes.js
index 9acf60785bc..bc52f9588cc 100755
--- a/lib/ajax/section_classes.js
+++ b/lib/ajax/section_classes.js
@@ -736,7 +736,7 @@ resource_class.prototype.indent_left = function() {
         }
         return false;
     }
-    var oldindent = indentdiv.classList.toString().match(/mod-indent-(\d{1,})/);
+    var oldindent = indentdiv.className.match(/mod-indent-(\d{1,})/);
     if (oldindent && oldindent[1] > 0) {
         oldindent = oldindent[1];
     } else {
@@ -767,7 +767,7 @@ resource_class.prototype.indent_right = function() {
         }
         return false;
     }
-    var oldindent = indentdiv.classList.toString().match(/mod-indent-(\d{1,})/);
+    var oldindent = indentdiv.className.match(/mod-indent-(\d{1,})/);
     if (oldindent && oldindent[1] >= 0) {
         oldindent = oldindent[1];
         var newindent = parseFloat(oldindent) + 1;