diff --git a/src/Symfony/Component/DependencyInjection/Loader/Configurator/ContainerConfigurator.php b/src/Symfony/Component/DependencyInjection/Loader/Configurator/ContainerConfigurator.php
index 22fc92727a..8ea04119d8 100644
--- a/src/Symfony/Component/DependencyInjection/Loader/Configurator/ContainerConfigurator.php
+++ b/src/Symfony/Component/DependencyInjection/Loader/Configurator/ContainerConfigurator.php
@@ -16,6 +16,7 @@ use Symfony\Component\DependencyInjection\Argument\TaggedIteratorArgument;
 use Symfony\Component\DependencyInjection\ContainerBuilder;
 use Symfony\Component\DependencyInjection\Definition;
 use Symfony\Component\DependencyInjection\Exception\InvalidArgumentException;
+use Symfony\Component\DependencyInjection\Extension\ExtensionInterface;
 use Symfony\Component\DependencyInjection\Loader\PhpFileLoader;
 use Symfony\Component\ExpressionLanguage\Expression;
 
@@ -45,7 +46,7 @@ class ContainerConfigurator extends AbstractConfigurator
     final public function extension(string $namespace, array $config)
     {
         if (!$this->container->hasExtension($namespace)) {
-            $extensions = array_filter(array_map(function ($ext) { return $ext->getAlias(); }, $this->container->getExtensions()));
+            $extensions = array_filter(array_map(function (ExtensionInterface $ext) { return $ext->getAlias(); }, $this->container->getExtensions()));
             throw new InvalidArgumentException(sprintf(
                 'There is no extension able to load the configuration for "%s" (in %s). Looked for namespace "%s", found %s',
                 $namespace,
diff --git a/src/Symfony/Component/DependencyInjection/Tests/Loader/XmlFileLoaderTest.php b/src/Symfony/Component/DependencyInjection/Tests/Loader/XmlFileLoaderTest.php
index fb80cd4936..7e0ce38719 100644
--- a/src/Symfony/Component/DependencyInjection/Tests/Loader/XmlFileLoaderTest.php
+++ b/src/Symfony/Component/DependencyInjection/Tests/Loader/XmlFileLoaderTest.php
@@ -13,6 +13,7 @@ namespace Symfony\Component\DependencyInjection\Tests\Loader;
 
 use PHPUnit\Framework\TestCase;
 use Symfony\Component\DependencyInjection\Argument\IteratorArgument;
+use Symfony\Component\DependencyInjection\Argument\BoundArgument;
 use Symfony\Component\DependencyInjection\ContainerBuilder;
 use Symfony\Component\DependencyInjection\Reference;
 use Symfony\Component\DependencyInjection\Loader\XmlFileLoader;
@@ -776,7 +777,7 @@ class XmlFileLoaderTest extends TestCase
             '$foo' => array(null),
             '$quz' => 'quz',
             '$factory' => 'factory',
-        ), array_map(function ($v) { return $v->getValues()[0]; }, $definition->getBindings()));
+        ), array_map(function (BoundArgument $v) { return $v->getValues()[0]; }, $definition->getBindings()));
         $this->assertEquals(array(
             'quz',
             null,
@@ -793,6 +794,6 @@ class XmlFileLoaderTest extends TestCase
             'NonExistent' => null,
             '$quz' => 'quz',
             '$factory' => 'factory',
-        ), array_map(function ($v) { return $v->getValues()[0]; }, $definition->getBindings()));
+        ), array_map(function (BoundArgument $v) { return $v->getValues()[0]; }, $definition->getBindings()));
     }
 }
diff --git a/src/Symfony/Component/DependencyInjection/Tests/Loader/YamlFileLoaderTest.php b/src/Symfony/Component/DependencyInjection/Tests/Loader/YamlFileLoaderTest.php
index ac11c92ffa..8ddc15f888 100644
--- a/src/Symfony/Component/DependencyInjection/Tests/Loader/YamlFileLoaderTest.php
+++ b/src/Symfony/Component/DependencyInjection/Tests/Loader/YamlFileLoaderTest.php
@@ -12,6 +12,7 @@
 namespace Symfony\Component\DependencyInjection\Tests\Loader;
 
 use PHPUnit\Framework\TestCase;
+use Symfony\Component\DependencyInjection\Argument\BoundArgument;
 use Symfony\Component\DependencyInjection\Argument\IteratorArgument;
 use Symfony\Component\DependencyInjection\ContainerBuilder;
 use Symfony\Component\DependencyInjection\Reference;
@@ -719,7 +720,7 @@ class YamlFileLoaderTest extends TestCase
             '$foo' => array(null),
             '$quz' => 'quz',
             '$factory' => 'factory',
-        ), array_map(function ($v) { return $v->getValues()[0]; }, $definition->getBindings()));
+        ), array_map(function (BoundArgument $v) { return $v->getValues()[0]; }, $definition->getBindings()));
         $this->assertEquals(array(
             'quz',
             null,
@@ -736,6 +737,6 @@ class YamlFileLoaderTest extends TestCase
             'NonExistent' => null,
             '$quz' => 'quz',
             '$factory' => 'factory',
-        ), array_map(function ($v) { return $v->getValues()[0]; }, $definition->getBindings()));
+        ), array_map(function (BoundArgument $v) { return $v->getValues()[0]; }, $definition->getBindings()));
     }
 }