diff --git a/wp-includes/blocks.php b/wp-includes/blocks.php
index 62ba1843d7..f6c8f32706 100644
--- a/wp-includes/blocks.php
+++ b/wp-includes/blocks.php
@@ -425,9 +425,12 @@ function unregister_block_type( $name ) {
 function has_blocks( $post = null ) {
 	if ( ! is_string( $post ) ) {
 		$wp_post = get_post( $post );
-		if ( $wp_post instanceof WP_Post ) {
-			$post = $wp_post->post_content;
+
+		if ( ! $wp_post instanceof WP_Post ) {
+			return false;
 		}
+
+		$post = $wp_post->post_content;
 	}
 
 	return false !== strpos( (string) $post, '<!-- wp:' );
diff --git a/wp-includes/version.php b/wp-includes/version.php
index 8ac87d7b55..87239b7ad0 100644
--- a/wp-includes/version.php
+++ b/wp-includes/version.php
@@ -16,7 +16,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '6.1-alpha-53857';
+$wp_version = '6.1-alpha-53858';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.