diff --git a/src/wp-includes/comment-template.php b/src/wp-includes/comment-template.php
index b6dff4e527..1c54a45310 100644
--- a/src/wp-includes/comment-template.php
+++ b/src/wp-includes/comment-template.php
@@ -2176,12 +2176,13 @@ function comment_form( $args = array(), $post_id = null ) {
 
 	$req      = get_option( 'require_name_email' );
 	$aria_req = ( $req ? " aria-required='true'" : '' );
+	$html_req = ( $req ? " required='required'" : '' );
 	$html5    = 'html5' === $args['format'];
 	$fields   =  array(
 		'author' => '<p class="comment-form-author">' . '<label for="author">' . __( 'Name' ) . ( $req ? ' <span class="required">*</span>' : '' ) . '</label> ' .
-		            '<input id="author" name="author" type="text" value="' . esc_attr( $commenter['comment_author'] ) . '" size="30"' . $aria_req . ' /></p>',
+		            '<input id="author" name="author" type="text" value="' . esc_attr( $commenter['comment_author'] ) . '" size="30"' . $aria_req . $html_req . ' /></p>',
 		'email'  => '<p class="comment-form-email"><label for="email">' . __( 'Email' ) . ( $req ? ' <span class="required">*</span>' : '' ) . '</label> ' .
-		            '<input id="email" name="email" ' . ( $html5 ? 'type="email"' : 'type="text"' ) . ' value="' . esc_attr(  $commenter['comment_author_email'] ) . '" size="30" aria-describedby="email-notes"' . $aria_req . ' /></p>',
+		            '<input id="email" name="email" ' . ( $html5 ? 'type="email"' : 'type="text"' ) . ' value="' . esc_attr(  $commenter['comment_author_email'] ) . '" size="30" aria-describedby="email-notes"' . $aria_req . $html_req  . ' /></p>',
 		'url'    => '<p class="comment-form-url"><label for="url">' . __( 'Website' ) . '</label> ' .
 		            '<input id="url" name="url" ' . ( $html5 ? 'type="url"' : 'type="text"' ) . ' value="' . esc_attr( $commenter['comment_author_url'] ) . '" size="30" /></p>',
 	);
@@ -2198,7 +2199,7 @@ function comment_form( $args = array(), $post_id = null ) {
 	$fields = apply_filters( 'comment_form_default_fields', $fields );
 	$defaults = array(
 		'fields'               => $fields,
-		'comment_field'        => '<p class="comment-form-comment"><label for="comment">' . _x( 'Comment', 'noun' ) . '</label> <textarea id="comment" name="comment" cols="45" rows="8" aria-describedby="form-allowed-tags" aria-required="true"></textarea></p>',
+		'comment_field'        => '<p class="comment-form-comment"><label for="comment">' . _x( 'Comment', 'noun' ) . '</label> <textarea id="comment" name="comment" cols="45" rows="8" aria-describedby="form-allowed-tags" aria-required="true" required="required"></textarea></p>',
 		/** This filter is documented in wp-includes/link-template.php */
 		'must_log_in'          => '<p class="must-log-in">' . sprintf( __( 'You must be <a href="%s">logged in</a> to post a comment.' ), wp_login_url( apply_filters( 'the_permalink', get_permalink( $post_id ) ) ) ) . '</p>',
 		/** This filter is documented in wp-includes/link-template.php */