diff --git a/src/Symfony/Bundle/SecurityBundle/Tests/DependencyInjection/Fixtures/php/argon2i_encoder.php b/src/Symfony/Bundle/SecurityBundle/Tests/DependencyInjection/Fixtures/php/argon2i_encoder.php
index 7276f97e6b..ddac043692 100644
--- a/src/Symfony/Bundle/SecurityBundle/Tests/DependencyInjection/Fixtures/php/argon2i_encoder.php
+++ b/src/Symfony/Bundle/SecurityBundle/Tests/DependencyInjection/Fixtures/php/argon2i_encoder.php
@@ -1,6 +1,6 @@
 <?php
 
-$this->load('container1.php', $container);
+$this->load('container1.php');
 
 $container->loadFromExtension('security', [
     'encoders' => [
diff --git a/src/Symfony/Bundle/SecurityBundle/Tests/DependencyInjection/Fixtures/php/bcrypt_encoder.php b/src/Symfony/Bundle/SecurityBundle/Tests/DependencyInjection/Fixtures/php/bcrypt_encoder.php
index 1afad79e4f..d4511aeb55 100644
--- a/src/Symfony/Bundle/SecurityBundle/Tests/DependencyInjection/Fixtures/php/bcrypt_encoder.php
+++ b/src/Symfony/Bundle/SecurityBundle/Tests/DependencyInjection/Fixtures/php/bcrypt_encoder.php
@@ -1,6 +1,6 @@
 <?php
 
-$this->load('container1.php', $container);
+$this->load('container1.php');
 
 $container->loadFromExtension('security', [
     'encoders' => [
diff --git a/src/Symfony/Bundle/SecurityBundle/Tests/DependencyInjection/Fixtures/php/migrating_encoder.php b/src/Symfony/Bundle/SecurityBundle/Tests/DependencyInjection/Fixtures/php/migrating_encoder.php
index 14c008be9d..c7ad9f02ab 100644
--- a/src/Symfony/Bundle/SecurityBundle/Tests/DependencyInjection/Fixtures/php/migrating_encoder.php
+++ b/src/Symfony/Bundle/SecurityBundle/Tests/DependencyInjection/Fixtures/php/migrating_encoder.php
@@ -1,6 +1,6 @@
 <?php
 
-$this->load('container1.php', $container);
+$this->load('container1.php');
 
 $container->loadFromExtension('security', [
     'encoders' => [
diff --git a/src/Symfony/Component/DependencyInjection/Loader/FileLoader.php b/src/Symfony/Component/DependencyInjection/Loader/FileLoader.php
index d553ca7072..f8f9fc4523 100644
--- a/src/Symfony/Component/DependencyInjection/Loader/FileLoader.php
+++ b/src/Symfony/Component/DependencyInjection/Loader/FileLoader.php
@@ -50,7 +50,7 @@ abstract class FileLoader extends BaseFileLoader
      *
      * @param bool|string $ignoreErrors Whether errors should be ignored; pass "not_found" to ignore only when the loaded resource is not found
      */
-    public function import($resource, $type = null, $ignoreErrors = false, $sourceResource = null, $exclude = null)
+    public function import($resource, string $type = null, $ignoreErrors = false, string $sourceResource = null, $exclude = null)
     {
         $args = \func_get_args();
 
@@ -87,7 +87,7 @@ abstract class FileLoader extends BaseFileLoader
      * @param string               $resource  The directory to look for classes, glob-patterns allowed
      * @param string|string[]|null $exclude   A globbed path of files to exclude or an array of globbed paths of files to exclude
      */
-    public function registerClasses(Definition $prototype, $namespace, $resource, $exclude = null)
+    public function registerClasses(Definition $prototype, string $namespace, string $resource, $exclude = null)
     {
         if ('\\' !== substr($namespace, -1)) {
             throw new InvalidArgumentException(sprintf('Namespace prefix must end with a "\\": "%s".', $namespace));
@@ -134,10 +134,8 @@ abstract class FileLoader extends BaseFileLoader
 
     /**
      * Registers a definition in the container with its instanceof-conditionals.
-     *
-     * @param string $id
      */
-    protected function setDefinition($id, Definition $definition)
+    protected function setDefinition(string $id, Definition $definition)
     {
         $this->container->removeBindings($id);
 
diff --git a/src/Symfony/Component/DependencyInjection/Loader/PhpFileLoader.php b/src/Symfony/Component/DependencyInjection/Loader/PhpFileLoader.php
index 196baf622b..5c7b628eab 100644
--- a/src/Symfony/Component/DependencyInjection/Loader/PhpFileLoader.php
+++ b/src/Symfony/Component/DependencyInjection/Loader/PhpFileLoader.php
@@ -28,7 +28,7 @@ class PhpFileLoader extends FileLoader
     /**
      * {@inheritdoc}
      */
-    public function load($resource, $type = null)
+    public function load($resource, string $type = null)
     {
         // the container and loader variables are exposed to the included file below
         $container = $this->container;
diff --git a/src/Symfony/Component/DependencyInjection/Tests/Loader/GlobFileLoaderTest.php b/src/Symfony/Component/DependencyInjection/Tests/Loader/GlobFileLoaderTest.php
index 493e935611..c7557ee690 100644
--- a/src/Symfony/Component/DependencyInjection/Tests/Loader/GlobFileLoaderTest.php
+++ b/src/Symfony/Component/DependencyInjection/Tests/Loader/GlobFileLoaderTest.php
@@ -38,7 +38,7 @@ class GlobFileLoaderTest extends TestCase
 
 class GlobFileLoaderWithoutImport extends GlobFileLoader
 {
-    public function import($resource, $type = null, $ignoreErrors = false, $sourceResource = null, $exclude = null)
+    public function import($resource, string $type = null, $ignoreErrors = false, string $sourceResource = null, $exclude = null)
     {
     }
 }