diff --git a/wp-admin/load-styles.php b/wp-admin/load-styles.php
index d75cfbe8d8..eb05554de2 100644
--- a/wp-admin/load-styles.php
+++ b/wp-admin/load-styles.php
@@ -73,7 +73,8 @@ foreach ( $load as $handle ) {
 
 	$content = get_file( $path ) . "\n";
 
-	if ( str_starts_with( $style->src, '/' . WPINC . '/css/' ) ) {
+	// str_starts_with() is not used here, as wp-includes/compat.php is not loaded in this file.
+	if ( 0 === strpos( $style->src, '/' . WPINC . '/css/' ) ) {
 		$content = str_replace( '../images/', '../' . WPINC . '/images/', $content );
 		$content = str_replace( '../js/tinymce/', '../' . WPINC . '/js/tinymce/', $content );
 		$content = str_replace( '../fonts/', '../' . WPINC . '/fonts/', $content );
diff --git a/wp-includes/version.php b/wp-includes/version.php
index bffa285efa..5f47cc00a3 100644
--- a/wp-includes/version.php
+++ b/wp-includes/version.php
@@ -16,7 +16,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '6.3-alpha-55709';
+$wp_version = '6.3-alpha-55710';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.