diff --git a/res/AnnotationParser.php b/res/AnnotationParser.php
index cc14060..db056b9 100644
--- a/res/AnnotationParser.php
+++ b/res/AnnotationParser.php
@@ -8,6 +8,9 @@
  * @license   http://www.gnu.org/copyleft/gpl.html GPL
  * @link      https://github.com/Ranyuen/Di
  */
+
+declare(strict_types=1);
+
 namespace Ranyuen\Di\Reflection;
 
 require_once 'vendor/hafriedlander/php-peg/autoloader.php';
diff --git a/src/Annotation/Inject.php b/src/Annotation/Inject.php
index 8588ab2..d163a20 100644
--- a/src/Annotation/Inject.php
+++ b/src/Annotation/Inject.php
@@ -9,6 +9,8 @@
  * @link      https://github.com/Ranyuen/Di
  */
 
+declare(strict_types=1);
+
 namespace Ranyuen\Di\Annotation;
 
 use Ranyuen\Di\Reflection\AbstractAnnotation;
diff --git a/src/Annotation/Named.php b/src/Annotation/Named.php
index bc48dac..071e0cc 100644
--- a/src/Annotation/Named.php
+++ b/src/Annotation/Named.php
@@ -9,6 +9,8 @@
  * @link      https://github.com/Ranyuen/Di
  */
 
+declare(strict_types=1);
+
 namespace Ranyuen\Di\Annotation;
 
 use Ranyuen\Di\Reflection\AbstractAnnotation;
diff --git a/src/Annotation/Wrap.php b/src/Annotation/Wrap.php
index 771f2c2..bc53813 100644
--- a/src/Annotation/Wrap.php
+++ b/src/Annotation/Wrap.php
@@ -9,6 +9,8 @@
  * @link      https://github.com/Ranyuen/Di
  */
 
+declare(strict_types=1);
+
 namespace Ranyuen\Di\Annotation;
 
 use Ranyuen\Di\Reflection\AbstractAnnotation;
diff --git a/src/Container.php b/src/Container.php
index 0a313de..832966a 100644
--- a/src/Container.php
+++ b/src/Container.php
@@ -9,6 +9,8 @@
  * @link      https://github.com/Ranyuen/Di
  */
 
+declare(strict_types=1);
+
 namespace Ranyuen\Di;
 
 use Pimple;
diff --git a/src/Dispatcher/Dispatcher.php b/src/Dispatcher/Dispatcher.php
index 0fa31f5..6dd2fab 100644
--- a/src/Dispatcher/Dispatcher.php
+++ b/src/Dispatcher/Dispatcher.php
@@ -9,6 +9,8 @@
  * @link      https://github.com/Ranyuen/Di
  */
 
+declare(strict_types=1);
+
 namespace Ranyuen\Di\Dispatcher;
 
 use Ranyuen\Di\Container;
diff --git a/src/Dispatcher/NakedDispatcher.php b/src/Dispatcher/NakedDispatcher.php
index 809db33..ddf5bb1 100644
--- a/src/Dispatcher/NakedDispatcher.php
+++ b/src/Dispatcher/NakedDispatcher.php
@@ -9,6 +9,8 @@
  * @link      https://github.com/Ranyuen/Di
  */
 
+declare(strict_types=1);
+
 namespace Ranyuen\Di\Dispatcher;
 
 use Ranyuen\Di\Container;
diff --git a/src/Dispatcher/ParametrizedInvokable.php b/src/Dispatcher/ParametrizedInvokable.php
index 440e1b8..94b6107 100644
--- a/src/Dispatcher/ParametrizedInvokable.php
+++ b/src/Dispatcher/ParametrizedInvokable.php
@@ -9,6 +9,8 @@
  * @link      https://github.com/Ranyuen/Di
  */
 
+declare(strict_types=1);
+
 namespace Ranyuen\Di\Dispatcher;
 
 /**
diff --git a/src/InjectorCache.php b/src/InjectorCache.php
index 28de2a2..bd4a32d 100644
--- a/src/InjectorCache.php
+++ b/src/InjectorCache.php
@@ -9,6 +9,8 @@
  * @link      https://github.com/Ranyuen/Di
  */
 
+declare(strict_types=1);
+
 namespace Ranyuen\Di;
 
 use Ranyuen\Di\Dispatcher\NakedDispatcher;
diff --git a/src/Reflection/AnnotationException.php b/src/Reflection/AnnotationException.php
index ff90a2b..44c45bb 100644
--- a/src/Reflection/AnnotationException.php
+++ b/src/Reflection/AnnotationException.php
@@ -9,6 +9,8 @@
  * @link      https://github.com/Ranyuen/Di
  */
 
+declare(strict_types=1);
+
 namespace Ranyuen\Di\Reflection;
 
 /**
diff --git a/src/Reflection/AnnotationParser.peg.inc b/src/Reflection/AnnotationParser.peg.inc
index 03b2a9e..bccab78 100644
--- a/src/Reflection/AnnotationParser.peg.inc
+++ b/src/Reflection/AnnotationParser.peg.inc
@@ -8,6 +8,9 @@
  * @license   http://www.gnu.org/copyleft/gpl.html GPL
  * @link      https://github.com/Ranyuen/Di
  */
+
+declare(strict_types=1);
+
 namespace Ranyuen\Di\Reflection;
 
 require_once 'vendor/hafriedlander/php-peg/autoloader.php';
diff --git a/src/Reflection/KeyReflector.php b/src/Reflection/KeyReflector.php
index 757ec98..e9f416a 100644
--- a/src/Reflection/KeyReflector.php
+++ b/src/Reflection/KeyReflector.php
@@ -9,6 +9,8 @@
  * @link      https://github.com/Ranyuen/Di
  */
 
+declare(strict_types=1);
+
 namespace Ranyuen\Di\Reflection;
 
 use Ranyuen\Di\Annotation\Inject;
diff --git a/src/Reflection/Type.php b/src/Reflection/Type.php
index 6ea5860..b06c740 100644
--- a/src/Reflection/Type.php
+++ b/src/Reflection/Type.php
@@ -9,6 +9,8 @@
  * @link      https://github.com/Ranyuen/Di
  */
 
+declare(strict_types=1);
+
 namespace Ranyuen\Di\Reflection;
 
 use Doctrine\Common\Annotations\PhpParser;
diff --git a/src/ServiceProviderInterface.php b/src/ServiceProviderInterface.php
index b4b0cdd..447aa86 100644
--- a/src/ServiceProviderInterface.php
+++ b/src/ServiceProviderInterface.php
@@ -9,6 +9,8 @@
  * @link      https://github.com/Ranyuen/Di
  */
 
+declare(strict_types=1);
+
 namespace Ranyuen\Di;
 
 /**