diff --git a/src/Symfony/Component/HttpKernel/Controller/ArgumentResolver/DefaultValueResolver.php b/src/Symfony/Component/HttpKernel/Controller/ArgumentResolver/DefaultValueResolver.php
index 0962dab885..1af03651c3 100644
--- a/src/Symfony/Component/HttpKernel/Controller/ArgumentResolver/DefaultValueResolver.php
+++ b/src/Symfony/Component/HttpKernel/Controller/ArgumentResolver/DefaultValueResolver.php
@@ -27,7 +27,7 @@ final class DefaultValueResolver implements ArgumentValueResolverInterface
      */
     public function supports(Request $request, ArgumentMetadata $argument)
     {
-        return $argument->hasDefaultValue() || $argument->isNullable();
+        return $argument->hasDefaultValue() || ($argument->isNullable() && !$argument->isVariadic());
     }
 
     /**
diff --git a/src/Symfony/Component/HttpKernel/ControllerMetadata/ArgumentMetadata.php b/src/Symfony/Component/HttpKernel/ControllerMetadata/ArgumentMetadata.php
index 72c294f3a3..32316a8d51 100644
--- a/src/Symfony/Component/HttpKernel/ControllerMetadata/ArgumentMetadata.php
+++ b/src/Symfony/Component/HttpKernel/ControllerMetadata/ArgumentMetadata.php
@@ -40,7 +40,7 @@ class ArgumentMetadata
         $this->isVariadic = $isVariadic;
         $this->hasDefaultValue = $hasDefaultValue;
         $this->defaultValue = $defaultValue;
-        $this->isNullable = (bool) $isNullable;
+        $this->isNullable = $isNullable || null === $type || ($hasDefaultValue && null === $defaultValue);
     }
 
     /**
@@ -88,7 +88,7 @@ class ArgumentMetadata
     }
 
     /**
-     * Returns whether the argument is nullable in PHP 7.1 or higher.
+     * Returns whether the argument accepts null values.
      *
      * @return bool
      */
diff --git a/src/Symfony/Component/HttpKernel/ControllerMetadata/ArgumentMetadataFactory.php b/src/Symfony/Component/HttpKernel/ControllerMetadata/ArgumentMetadataFactory.php
index efe5966894..ad6c395ee7 100644
--- a/src/Symfony/Component/HttpKernel/ControllerMetadata/ArgumentMetadataFactory.php
+++ b/src/Symfony/Component/HttpKernel/ControllerMetadata/ArgumentMetadataFactory.php
@@ -58,7 +58,7 @@ final class ArgumentMetadataFactory implements ArgumentMetadataFactoryInterface
         }
 
         foreach ($reflection->getParameters() as $param) {
-            $arguments[] = new ArgumentMetadata($param->getName(), $this->getType($param), $this->isVariadic($param), $this->hasDefaultValue($param), $this->getDefaultValue($param), $this->isNullable($param));
+            $arguments[] = new ArgumentMetadata($param->getName(), $this->getType($param), $this->isVariadic($param), $this->hasDefaultValue($param), $this->getDefaultValue($param), $param->allowsNull());
         }
 
         return $arguments;
@@ -88,23 +88,6 @@ final class ArgumentMetadataFactory implements ArgumentMetadataFactoryInterface
         return $parameter->isDefaultValueAvailable();
     }
 
-    /**
-     * Returns if the argument is allowed to be null but is still mandatory.
-     *
-     * @param \ReflectionParameter $parameter
-     *
-     * @return bool
-     */
-    private function isNullable(\ReflectionParameter $parameter)
-    {
-        if ($this->supportsParameterType) {
-            return null !== ($type = $parameter->getType()) && $type->allowsNull();
-        }
-
-        // fallback for supported php 5.x versions
-        return $this->hasDefaultValue($parameter) && null === $this->getDefaultValue($parameter);
-    }
-
     /**
      * Returns a default value if available.
      *
@@ -127,7 +110,16 @@ final class ArgumentMetadataFactory implements ArgumentMetadataFactoryInterface
     private function getType(\ReflectionParameter $parameter)
     {
         if ($this->supportsParameterType) {
-            return $parameter->hasType() ? (string) $parameter->getType() : null;
+            if (!$type = $parameter->getType()) {
+                return;
+            }
+            $typeName = $type instanceof \ReflectionNamedType ? $type->getName() : $type->__toString();
+            if ('array' === $typeName && !$type->isBuiltin()) {
+                // Special case for HHVM with variadics
+                return;
+            }
+
+            return $typeName;
         }
 
         if ($parameter->isArray()) {
diff --git a/src/Symfony/Component/HttpKernel/Tests/ControllerMetadata/ArgumentMetadataFactoryTest.php b/src/Symfony/Component/HttpKernel/Tests/ControllerMetadata/ArgumentMetadataFactoryTest.php
index 49931f052c..1ca9a3c798 100644
--- a/src/Symfony/Component/HttpKernel/Tests/ControllerMetadata/ArgumentMetadataFactoryTest.php
+++ b/src/Symfony/Component/HttpKernel/Tests/ControllerMetadata/ArgumentMetadataFactoryTest.php
@@ -121,7 +121,7 @@ class ArgumentMetadataFactoryTest extends \PHPUnit_Framework_TestCase
             new ArgumentMetadata('foo', 'string', false, false, null, true),
             new ArgumentMetadata('bar', \stdClass::class, false, false, null, true),
             new ArgumentMetadata('baz', 'string', false, true, 'value', true),
-            new ArgumentMetadata('mandatory', null, false, false, null),
+            new ArgumentMetadata('mandatory', null, false, false, null, true),
         ), $arguments);
     }