diff --git a/question/type/essay/renderer.php b/question/type/essay/renderer.php
index a0cb56969eb..8b09685e0b2 100644
--- a/question/type/essay/renderer.php
+++ b/question/type/essay/renderer.php
@@ -259,7 +259,7 @@ class qtype_essay_format_editor_renderer extends plugin_renderer_base {
                 $this->class_name() . ' qtype_essay_response'));
 
         $output .= html_writer::tag('div', html_writer::tag('textarea', s($response),
-                array('id' => $id, 'name' => $inputname, 'rows' => $lines, 'cols' => 60)));
+                array('id' => $id, 'name' => $inputname, 'rows' => $lines, 'cols' => 60, 'class' => 'form-control')));
 
         $output .= html_writer::start_tag('div');
         if (count($formats) == 1) {
@@ -450,7 +450,7 @@ class qtype_essay_format_plain_renderer extends plugin_renderer_base {
      * @return string the HTML for the textarea.
      */
     protected function textarea($response, $lines, $attributes) {
-        $attributes['class'] = $this->class_name() . ' qtype_essay_response';
+        $attributes['class'] = $this->class_name() . ' qtype_essay_response form-control';
         $attributes['rows'] = $lines;
         $attributes['cols'] = 60;
         return html_writer::tag('textarea', s($response), $attributes);