diff --git a/src/pocketmine/GlobalConstants.php b/src/pocketmine/GlobalConstants.php
index d3b4a9f9a..e32d07c04 100644
--- a/src/pocketmine/GlobalConstants.php
+++ b/src/pocketmine/GlobalConstants.php
@@ -19,6 +19,8 @@
  *
 */
 
+declare(strict_types=1);
+
 // composer autoload doesn't use require_once and also pthreads can inherit things
 if(defined('pocketmine\_GLOBAL_CONSTANTS_INCLUDED')){
 	return;