diff --git a/packages/block-library/src/rss/index.php b/packages/block-library/src/rss/index.php
index b5fe3abaf563be..006cffcb081c22 100644
--- a/packages/block-library/src/rss/index.php
+++ b/packages/block-library/src/rss/index.php
@@ -79,8 +79,17 @@ function render_block_core_rss( $attributes ) {
 		$list_items .= "<li class='wp-block-rss__item'>{$title}{$date}{$author}{$excerpt}</li>";
 	}
 
-	$classes           = 'grid' === $attributes['blockLayout'] ? ' is-grid columns-' . $attributes['columns'] : '';
-	$list_items_markup = "<ul class='wp-block-rss{$classes}'>{$list_items}</ul>";
+	$class = 'wp-block-rss';
+
+	if ( 'grid' === $attributes['blockLayout'] ) {
+		$class .= ' is-grid columns-' . $attributes['columns'];
+	}
+
+	if ( ! empty( $attributes['className'] ) ) {
+		$class .= ' ' . $attributes['className'];
+	}
+
+	$list_items_markup = "<ul class='{$class}'>{$list_items}</ul>";
 
 	// PHP 5.2 compatibility. See: http://simplepie.org/wiki/faq/i_m_getting_memory_leaks.
 	$rss->__destruct();
@@ -96,31 +105,26 @@ function register_block_core_rss() {
 	register_block_type( 'core/rss',
 		array(
 			'attributes'      => array(
-				'columns'        => array(
-					'type'    => 'number',
-					'default' => 2,
-				),
 				'blockLayout'    => array(
 					'type'    => 'string',
 					'default' => 'list',
 				),
-				'feedURL'        => array(
-					'type'    => 'string',
-					'default' => '',
+				'className'      => array(
+					'type' => 'string',
 				),
-				'itemsToShow'    => array(
+				'columns'        => array(
 					'type'    => 'number',
-					'default' => 5,
+					'default' => 2,
 				),
-				'displayExcerpt' => array(
+				'displayAuthor'  => array(
 					'type'    => 'boolean',
 					'default' => false,
 				),
-				'displayAuthor'  => array(
+				'displayDate'    => array(
 					'type'    => 'boolean',
 					'default' => false,
 				),
-				'displayDate'    => array(
+				'displayExcerpt' => array(
 					'type'    => 'boolean',
 					'default' => false,
 				),
@@ -128,6 +132,14 @@ function register_block_core_rss() {
 					'type'    => 'number',
 					'default' => 55,
 				),
+				'feedURL'        => array(
+					'type'    => 'string',
+					'default' => '',
+				),
+				'itemsToShow'    => array(
+					'type'    => 'number',
+					'default' => 5,
+				),
 			),
 			'render_callback' => 'render_block_core_rss',
 		)