diff --git a/platform/php/MailChecker.php b/platform/php/MailChecker.php
index 5853edf3..ff152e29 100644
--- a/platform/php/MailChecker.php
+++ b/platform/php/MailChecker.php
@@ -12,7 +12,7 @@
  */
 class MailChecker
 {
-    private static array $blacklist;
+    private static $blacklist;
 
     public static function init(): void
     {