diff --git a/inc/custom-comments.php b/inc/custom-comments.php
index cf38f26..6292a74 100644
--- a/inc/custom-comments.php
+++ b/inc/custom-comments.php
@@ -8,61 +8,82 @@
 // Exit if accessed directly.
 defined( 'ABSPATH' ) || exit;
 
-// Comments form.
+// Add Bootstrap classes to comment form fields.
 add_filter( 'comment_form_default_fields', 'understrap_bootstrap_comment_form_fields' );
 
-/**
- * Creates the comments form.
- *
- * @param string $fields Form fields.
- *
- * @return array
- */
-
 if ( ! function_exists( 'understrap_bootstrap_comment_form_fields' ) ) {
-
+	/**
+	 * Add Bootstrap classes to WP's comment form default fields.
+	 *
+	 * @param array $fields {
+	 *     Default comment fields.
+	 *
+	 *     @type string $author  Comment author field HTML.
+	 *     @type string $email   Comment author email field HTML.
+	 *     @type string $url     Comment author URL field HTML.
+	 *     @type string $cookies Comment cookie opt-in field HTML.
+	 * }
+	 *
+	 * @return array
+	 */
 	function understrap_bootstrap_comment_form_fields( $fields ) {
-		$commenter = wp_get_current_commenter();
-		$req       = get_option( 'require_name_email' );
-		$aria_req  = ( $req ? " aria-required='true'" : '' );
-		$html5     = current_theme_supports( 'html5', 'comment-form' ) ? 1 : 0;
-		$consent  = empty( $commenter['comment_author_email'] ) ? '' : ' checked="checked"';
-		$fields    = array(
-			'author'  => '<div class="form-group comment-form-author"><label for="author">' . __( 'Name',
-					'understrap' ) . ( $req ? ' <span class="required">*</span>' : '' ) . '</label> ' .
-			            '<input class="form-control" id="author" name="author" type="text" value="' . esc_attr( $commenter['comment_author'] ) . '" size="30"' . $aria_req . '></div>',
-			'email'   => '<div class="form-group comment-form-email"><label for="email">' . __( 'Email',
-					'understrap' ) . ( $req ? ' <span class="required">*</span>' : '' ) . '</label> ' .
-			            '<input class="form-control" id="email" name="email" ' . ( $html5 ? 'type="email"' : 'type="text"' ) . ' value="' . esc_attr( $commenter['comment_author_email'] ) . '" size="30"' . $aria_req . '></div>',
-			'url'     => '<div class="form-group comment-form-url"><label for="url">' . __( 'Website',
-					'understrap' ) . '</label> ' .
-			            '<input class="form-control" id="url" name="url" ' . ( $html5 ? 'type="url"' : 'type="text"' ) . ' value="' . esc_attr( $commenter['comment_author_url'] ) . '" size="30"></div>',
-			'cookies' => '<div class="form-group form-check comment-form-cookies-consent"><input class="form-check-input" id="wp-comment-cookies-consent" name="wp-comment-cookies-consent" type="checkbox" value="yes"' . $consent . ' /> ' .
-			         '<label class="form-check-label" for="wp-comment-cookies-consent">' . __( 'Save my name, email, and website in this browser for the next time I comment', 'understrap' ) . '</label></div>',
+
+		$replace = array(
+			'<p class="' => '<div class="form-group ',
+			'<input'     => '<input class="form-control" ',
+			'</p>'       => '</div>',
 		);
 
+		if ( isset( $fields['author'] ) ) {
+			$fields['author'] = strtr( $fields['author'], $replace );
+		}
+		if ( isset( $fields['email'] ) ) {
+			$fields['email'] = strtr( $fields['email'], $replace );
+		}
+		if ( isset( $fields['url'] ) ) {
+			$fields['url'] = strtr( $fields['url'], $replace );
+		}
+
+		$replace = array(
+			'<p class="' => '<div class="form-group form-check ',
+			'<input'     => '<input class="form-check-input" ',
+			'<label'     => '<label class="form-check-label" ',
+			'</p>'       => '</div>',
+		);
+		if ( isset( $fields['cookies'] ) ) {
+			$fields['cookies'] = strtr( $fields['cookies'], $replace );
+		}
+
 		return $fields;
 	}
-} // endif function_exists( 'understrap_bootstrap_comment_form_fields' )
+} // End of if function_exists( 'understrap_bootstrap_comment_form_fields' )
 
+// Add Bootstrap classes to comment form submit button and comment field.
 add_filter( 'comment_form_defaults', 'understrap_bootstrap_comment_form' );
 
-/**
- * Builds the form.
- *
- * @param string $args Arguments for form's fields.
- *
- * @return mixed
- */
-
 if ( ! function_exists( 'understrap_bootstrap_comment_form' ) ) {
-
+	/**
+	 * Builds the form.
+	 *
+	 * @param string[] $args Comment form arguments and fields.
+	 *
+	 * @return string[]
+	 */
 	function understrap_bootstrap_comment_form( $args ) {
-		$args['comment_field'] = '<div class="form-group comment-form-comment">
-	    <label for="comment">' . _x( 'Comment', 'noun', 'understrap' ) . ( ' <span class="required">*</span>' ) . '</label>
-	    <textarea class="form-control" id="comment" name="comment" aria-required="true" cols="45" rows="8"></textarea>
-	    </div>';
-		$args['class_submit']  = 'btn btn-secondary'; // since WP 4.1.
+		$replace = array(
+			'<p class="' => '<div class="form-group ',
+			'<textarea'  => '<textarea class="form-control" ',
+			'</p>'       => '</div>',
+		);
+
+		if ( isset( $args['comment_field'] ) ) {
+			$args['comment_field'] = strtr( $args['comment_field'], $replace );
+		}
+
+		if ( isset( $args['class_submit'] ) ) {
+			$args['class_submit'] = 'btn btn-secondary';
+		}
+
 		return $args;
 	}
-} // endif function_exists( 'understrap_bootstrap_comment_form' )
+} // End of if function_exists( 'understrap_bootstrap_comment_form' ).