diff --git a/src/wp-includes/class-phpmailer.php b/src/wp-includes/class-phpmailer.php
index b82f7ff613..796bd379f3 100644
--- a/src/wp-includes/class-phpmailer.php
+++ b/src/wp-includes/class-phpmailer.php
@@ -3,7 +3,9 @@
 /**
  * The PHPMailer class has been moved to the wp-includes/PHPMailer subdirectory and now uses the PHPMailer\PHPMailer namespace.
  */
-_deprecated_file( basename( __FILE__ ), '5.5.0', WPINC . '/PHPMailer/PHPMailer.php', __( 'The PHPMailer class has been moved to wp-includes/PHPMailer subdirectory and now uses the PHPMailer\PHPMailer namespace.' ) );
+if ( function_exists( '_deprecated_file' ) ) {
+	_deprecated_file( basename( __FILE__ ), '5.5.0', WPINC . '/PHPMailer/PHPMailer.php', __( 'The PHPMailer class has been moved to wp-includes/PHPMailer subdirectory and now uses the PHPMailer\PHPMailer namespace.' ) );
+}
 require __DIR__ . '/PHPMailer/PHPMailer.php';
 
 class_alias( PHPMailer\PHPMailer\PHPMailer::class, 'PHPMailer' );