diff --git a/src/wp-includes/class-wp-fatal-error-handler.php b/src/wp-includes/class-wp-fatal-error-handler.php
index 96958d10de..f17011cc33 100644
--- a/src/wp-includes/class-wp-fatal-error-handler.php
+++ b/src/wp-includes/class-wp-fatal-error-handler.php
@@ -37,7 +37,7 @@ class WP_Fatal_Error_Handler {
 				return;
 			}
 
-			if ( ! isset( $GLOBALS['wp_locale'] ) ) {
+			if ( ! isset( $GLOBALS['wp_locale'] ) && function_exists( 'load_default_textdomain' ) ) {
 				load_default_textdomain();
 			}
 
@@ -165,6 +165,10 @@ class WP_Fatal_Error_Handler {
 			require_once ABSPATH . WPINC . '/functions.php';
 		}
 
+		if ( ! class_exists( 'WP_Error' ) ) {
+			require_once ABSPATH . WPINC . '/class-wp-error.php';
+		}
+
 		if ( is_protected_endpoint() ) {
 			$message = __( 'The site is experiencing technical difficulties. Please check your site admin email inbox for instructions.' );
 		} else {