diff --git a/src/wp-includes/class-wp-theme-json.php b/src/wp-includes/class-wp-theme-json.php
index a299c8556ef66..77e790fd8fc5e 100644
--- a/src/wp-includes/class-wp-theme-json.php
+++ b/src/wp-includes/class-wp-theme-json.php
@@ -1477,6 +1477,9 @@ protected static function get_style_nodes( $theme_json, $selectors = array() ) {
 
 		if ( isset( $theme_json['styles']['elements'] ) ) {
 			foreach ( $theme_json['styles']['elements'] as $element => $node ) {
+				if ( ! isset( $theme_json['styles']['elements'][ $element ] ) || ! array_key_exists( $element, static::ELEMENTS ) ) {
+					continue;
+				}
 				$nodes[] = array(
 					'path'     => array( 'styles', 'elements', $element ),
 					'selector' => static::ELEMENTS[ $element ],