diff --git a/src/Traits/Test/Base/BaseTestCaseTrait.php b/src/Traits/Test/Base/BaseTestCaseTrait.php
index 11ec351..bdf852b 100644
--- a/src/Traits/Test/Base/BaseTestCaseTrait.php
+++ b/src/Traits/Test/Base/BaseTestCaseTrait.php
@@ -6,6 +6,8 @@
  * file that was distributed with this source code.
  */
 
+declare(strict_types=1);
+
 namespace Meritoo\Common\Traits\Test\Base;
 
 use DateTime;
diff --git a/src/Traits/Test/Base/BaseTypeTestCaseTrait.php b/src/Traits/Test/Base/BaseTypeTestCaseTrait.php
index e08c7b4..9a86368 100644
--- a/src/Traits/Test/Base/BaseTypeTestCaseTrait.php
+++ b/src/Traits/Test/Base/BaseTypeTestCaseTrait.php
@@ -6,6 +6,8 @@
  * file that was distributed with this source code.
  */
 
+declare(strict_types=1);
+
 namespace Meritoo\Common\Traits\Test\Base;
 
 use Generator;
diff --git a/src/Traits/ValueObject/HumanTrait.php b/src/Traits/ValueObject/HumanTrait.php
index a75bfa6..bfaea59 100644
--- a/src/Traits/ValueObject/HumanTrait.php
+++ b/src/Traits/ValueObject/HumanTrait.php
@@ -6,6 +6,8 @@
  * file that was distributed with this source code.
  */
 
+declare(strict_types=1);
+
 namespace Meritoo\Common\Traits\ValueObject;
 
 use DateTime;