diff --git a/src/wp-includes/block-supports/layout.php b/src/wp-includes/block-supports/layout.php
index 40542209d072c..bad9430136589 100644
--- a/src/wp-includes/block-supports/layout.php
+++ b/src/wp-includes/block-supports/layout.php
@@ -492,7 +492,7 @@ function wp_render_layout_support_flag( $block_content, $block ) {
 	*/
 	$inner_content_classnames = '';
 
-	if ( isset( $block['innerContent'][0] ) && 'string' === gettype( $block['innerContent'][0] ) ) {
+	if ( isset( $block['innerContent'][0] ) && 'string' === gettype( $block['innerContent'][0] ) && count( $block['innerContent'] ) > 1 ) {
 		$tags            = new WP_HTML_Tag_Processor( $block['innerContent'][0] );
 		$last_classnames = '';
 		while ( $tags->next_tag() ) {