diff --git a/wp-includes/block-supports/layout.php b/wp-includes/block-supports/layout.php
index 0d299b6536..274e0f4168 100644
--- a/wp-includes/block-supports/layout.php
+++ b/wp-includes/block-supports/layout.php
@@ -549,7 +549,7 @@ function wp_get_layout_style( $selector, $layout, $has_block_gap_support = false
 function wp_render_layout_support_flag( $block_content, $block ) {
 	$block_type            = WP_Block_Type_Registry::get_instance()->get_registered( $block['blockName'] );
 	$block_supports_layout = block_has_support( $block_type, 'layout', false ) || block_has_support( $block_type, '__experimentalLayout', false );
-	$layout_from_parent    = $block['attrs']['style']['layout']['selfStretch'] ?? null;
+	$layout_from_parent    = isset( $block['attrs']['style']['layout']['selfStretch'] ) ? $block['attrs']['style']['layout']['selfStretch'] : null;
 
 	if ( ! $block_supports_layout && ! $layout_from_parent ) {
 		return $block_content;
@@ -770,7 +770,7 @@ function wp_render_layout_support_flag( $block_content, $block ) {
 	 * @var string|null
 	 */
 	$inner_block_wrapper_classes = null;
-	$first_chunk                 = $block['innerContent'][0] ?? null;
+	$first_chunk                 = isset( $block['innerContent'][0] ) ? $block['innerContent'][0] : null;
 	if ( is_string( $first_chunk ) && count( $block['innerContent'] ) > 1 ) {
 		$first_chunk_processor = new WP_HTML_Tag_Processor( $first_chunk );
 		while ( $first_chunk_processor->next_tag() ) {
diff --git a/wp-includes/version.php b/wp-includes/version.php
index 3188b556f5..8301a7d4c2 100644
--- a/wp-includes/version.php
+++ b/wp-includes/version.php
@@ -16,7 +16,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '6.4-alpha-56699';
+$wp_version = '6.4-alpha-56700';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.