diff --git a/system/Commands/Utilities/ConfigCheck.php b/system/Commands/Utilities/ConfigCheck.php
index 3ab45cc25f1f..c42de1eb7566 100644
--- a/system/Commands/Utilities/ConfigCheck.php
+++ b/system/Commands/Utilities/ConfigCheck.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 /**
  * This file is part of CodeIgniter 4 framework.
  *
diff --git a/system/Helpers/Array/ArrayHelper.php b/system/Helpers/Array/ArrayHelper.php
index 5b359a761384..7215c6d2740a 100644
--- a/system/Helpers/Array/ArrayHelper.php
+++ b/system/Helpers/Array/ArrayHelper.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 /**
  * This file is part of CodeIgniter 4 framework.
  *
diff --git a/tests/system/Commands/Utilities/ConfigCheckTest.php b/tests/system/Commands/Utilities/ConfigCheckTest.php
index 664a9cf64b7a..e551a1ae94c6 100644
--- a/tests/system/Commands/Utilities/ConfigCheckTest.php
+++ b/tests/system/Commands/Utilities/ConfigCheckTest.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 /**
  * This file is part of CodeIgniter 4 framework.
  *