diff --git a/src/Middlewares/SetHeaderMiddleware.php b/src/Middlewares/SetHeaderMiddleware.php
index c62f8a1..0de1959 100644
--- a/src/Middlewares/SetHeaderMiddleware.php
+++ b/src/Middlewares/SetHeaderMiddleware.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace DragonCode\LaravelJsonResponse\Middlewares;
 
 use Closure;
diff --git a/src/ServiceProvider.php b/src/ServiceProvider.php
index 0d52d20..8bcb9ea 100644
--- a/src/ServiceProvider.php
+++ b/src/ServiceProvider.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace DragonCode\LaravelJsonResponse;
 
 use DragonCode\LaravelJsonResponse\Middlewares\SetHeaderMiddleware;
diff --git a/tests/Middlewares/AllTest.php b/tests/Middlewares/AllTest.php
index a4a2f9e..7810ef6 100644
--- a/tests/Middlewares/AllTest.php
+++ b/tests/Middlewares/AllTest.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Tests\Middlewares;
 
 use Lmc\HttpConstants\Header;
diff --git a/tests/Middlewares/ApiAndWebTest.php b/tests/Middlewares/ApiAndWebTest.php
index 4df071c..defdbb5 100644
--- a/tests/Middlewares/ApiAndWebTest.php
+++ b/tests/Middlewares/ApiAndWebTest.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Tests\Middlewares;
 
 use Lmc\HttpConstants\Header;
diff --git a/tests/Middlewares/OnlyApiTest.php b/tests/Middlewares/OnlyApiTest.php
index 9237592..1f69769 100644
--- a/tests/Middlewares/OnlyApiTest.php
+++ b/tests/Middlewares/OnlyApiTest.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Tests\Middlewares;
 
 use Lmc\HttpConstants\Header;
diff --git a/tests/Middlewares/OnlyWebTest.php b/tests/Middlewares/OnlyWebTest.php
index 815312b..b76a87f 100644
--- a/tests/Middlewares/OnlyWebTest.php
+++ b/tests/Middlewares/OnlyWebTest.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Tests\Middlewares;
 
 use Lmc\HttpConstants\Header;
diff --git a/tests/TestCase.php b/tests/TestCase.php
index 7018e1a..401ddcc 100644
--- a/tests/TestCase.php
+++ b/tests/TestCase.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Tests;
 
 use DragonCode\LaravelJsonResponse\ServiceProvider;