diff --git a/src/Symfony/Component/DependencyInjection/EnvVarProcessor.php b/src/Symfony/Component/DependencyInjection/EnvVarProcessor.php
index 1bb68a98cd92..43022ddb7b9d 100644
--- a/src/Symfony/Component/DependencyInjection/EnvVarProcessor.php
+++ b/src/Symfony/Component/DependencyInjection/EnvVarProcessor.php
@@ -129,8 +129,8 @@ public function getEnv($prefix, $name, \Closure $getEnv)
                 throw new RuntimeException(sprintf('Invalid JSON in env var "%s": '.json_last_error_msg(), $name));
             }
 
-            if (!is_array($env)) {
-                throw new RuntimeException(sprintf('Invalid JSON env var "%s": array expected, %s given.', $name, gettype($env)));
+            if (null !== $env && !is_array($env)) {
+                throw new RuntimeException(sprintf('Invalid JSON env var "%s": array or null expected, %s given.', $name, gettype($env)));
             }
 
             return $env;
diff --git a/src/Symfony/Component/DependencyInjection/Tests/Dumper/PhpDumperTest.php b/src/Symfony/Component/DependencyInjection/Tests/Dumper/PhpDumperTest.php
index cdeaac72cf78..89130902b4a1 100644
--- a/src/Symfony/Component/DependencyInjection/Tests/Dumper/PhpDumperTest.php
+++ b/src/Symfony/Component/DependencyInjection/Tests/Dumper/PhpDumperTest.php
@@ -432,6 +432,27 @@ public function testDumpedCsvEnvParameters()
         $this->assertSame(array('foo', 'bar'), $container->getParameter('hello'));
     }
 
+    public function testDumpedJsonEnvParameters()
+    {
+        $container = new ContainerBuilder();
+        $container->setParameter('env(foo)', '["foo","bar"]');
+        $container->setParameter('env(bar)', 'null');
+        $container->setParameter('hello', '%env(json:foo)%');
+        $container->setParameter('hello-bar', '%env(json:bar)%');
+        $container->compile();
+
+        $dumper = new PhpDumper($container);
+        $dumper->dump();
+
+        $this->assertStringEqualsFile(self::$fixturesPath.'/php/services_json_env.php', $dumper->dump(array('class' => 'Symfony_DI_PhpDumper_Test_JsonParameters')));
+
+        putenv('foobar="hello"');
+        require self::$fixturesPath.'/php/services_json_env.php';
+        $container = new \Symfony_DI_PhpDumper_Test_JsonParameters();
+        $this->assertSame(array('foo', 'bar'), $container->getParameter('hello'));
+        $this->assertNull($container->getParameter('hello-bar'));
+    }
+
     public function testCustomEnvParameters()
     {
         $container = new ContainerBuilder();
diff --git a/src/Symfony/Component/DependencyInjection/Tests/EnvVarProcessorTest.php b/src/Symfony/Component/DependencyInjection/Tests/EnvVarProcessorTest.php
index b1ee044e9e5c..79b3e47c79de 100644
--- a/src/Symfony/Component/DependencyInjection/Tests/EnvVarProcessorTest.php
+++ b/src/Symfony/Component/DependencyInjection/Tests/EnvVarProcessorTest.php
@@ -233,17 +233,29 @@ public function testGetEnvBase64()
         $this->assertSame('hello', $result);
     }
 
-    public function testGetEnvJson()
+    /**
+     * @dataProvider validJson
+     */
+    public function testGetEnvJson($value, $processed)
     {
         $processor = new EnvVarProcessor(new Container());
 
-        $result = $processor->getEnv('json', 'foo', function ($name) {
+        $result = $processor->getEnv('json', 'foo', function ($name) use ($value) {
             $this->assertSame('foo', $name);
 
-            return json_encode(array(1));
+            return $value;
         });
 
-        $this->assertSame(array(1), $result);
+        $this->assertSame($processed, $result);
+    }
+
+    public function validJson()
+    {
+        return array(
+            array('[1]', array(1)),
+            array('{"key": "value"}', array('key' => 'value')),
+            array(null, null),
+        );
     }
 
     /**
@@ -284,6 +296,7 @@ public function otherJsonValues()
             array(1.1),
             array(true),
             array(false),
+            array('foo'),
         );
     }
 
diff --git a/src/Symfony/Component/DependencyInjection/Tests/Fixtures/php/services_json_env.php b/src/Symfony/Component/DependencyInjection/Tests/Fixtures/php/services_json_env.php
new file mode 100644
index 000000000000..dd2930a424ba
--- /dev/null
+++ b/src/Symfony/Component/DependencyInjection/Tests/Fixtures/php/services_json_env.php
@@ -0,0 +1,138 @@
+<?php
+
+use Symfony\Component\DependencyInjection\Argument\RewindableGenerator;
+use Symfony\Component\DependencyInjection\ContainerInterface;
+use Symfony\Component\DependencyInjection\Container;
+use Symfony\Component\DependencyInjection\Exception\InvalidArgumentException;
+use Symfony\Component\DependencyInjection\Exception\LogicException;
+use Symfony\Component\DependencyInjection\Exception\RuntimeException;
+use Symfony\Component\DependencyInjection\ParameterBag\FrozenParameterBag;
+
+/**
+ * This class has been auto-generated
+ * by the Symfony Dependency Injection Component.
+ *
+ * @final since Symfony 3.3
+ */
+class Symfony_DI_PhpDumper_Test_JsonParameters extends Container
+{
+    private $parameters;
+    private $targetDirs = array();
+
+    /**
+     * @internal but protected for BC on cache:clear
+     */
+    protected $privates = array();
+
+    public function __construct()
+    {
+        $this->parameters = $this->getDefaultParameters();
+
+        $this->services = $this->privates = array();
+
+        $this->aliases = array();
+    }
+
+    public function reset()
+    {
+        $this->privates = array();
+        parent::reset();
+    }
+
+    public function compile()
+    {
+        throw new LogicException('You cannot compile a dumped container that was already compiled.');
+    }
+
+    public function isCompiled()
+    {
+        return true;
+    }
+
+    public function getRemovedIds()
+    {
+        return array(
+            'Psr\\Container\\ContainerInterface' => true,
+            'Symfony\\Component\\DependencyInjection\\ContainerInterface' => true,
+        );
+    }
+
+    public function getParameter($name)
+    {
+        $name = (string) $name;
+
+        if (!(isset($this->parameters[$name]) || isset($this->loadedDynamicParameters[$name]) || array_key_exists($name, $this->parameters))) {
+            throw new InvalidArgumentException(sprintf('The parameter "%s" must be defined.', $name));
+        }
+        if (isset($this->loadedDynamicParameters[$name])) {
+            return $this->loadedDynamicParameters[$name] ? $this->dynamicParameters[$name] : $this->getDynamicParameter($name);
+        }
+
+        return $this->parameters[$name];
+    }
+
+    public function hasParameter($name)
+    {
+        $name = (string) $name;
+
+        return isset($this->parameters[$name]) || isset($this->loadedDynamicParameters[$name]) || array_key_exists($name, $this->parameters);
+    }
+
+    public function setParameter($name, $value)
+    {
+        throw new LogicException('Impossible to call set() on a frozen ParameterBag.');
+    }
+
+    public function getParameterBag()
+    {
+        if (null === $this->parameterBag) {
+            $parameters = $this->parameters;
+            foreach ($this->loadedDynamicParameters as $name => $loaded) {
+                $parameters[$name] = $loaded ? $this->dynamicParameters[$name] : $this->getDynamicParameter($name);
+            }
+            $this->parameterBag = new FrozenParameterBag($parameters);
+        }
+
+        return $this->parameterBag;
+    }
+
+    private $loadedDynamicParameters = array(
+        'hello' => false,
+        'hello-bar' => false,
+    );
+    private $dynamicParameters = array();
+
+    /**
+     * Computes a dynamic parameter.
+     *
+     * @param string The name of the dynamic parameter to load
+     *
+     * @return mixed The value of the dynamic parameter
+     *
+     * @throws InvalidArgumentException When the dynamic parameter does not exist
+     */
+    private function getDynamicParameter($name)
+    {
+        switch ($name) {
+            case 'hello': $value = $this->getEnv('json:foo'); break;
+            case 'hello-bar': $value = $this->getEnv('json:bar'); break;
+            default: throw new InvalidArgumentException(sprintf('The dynamic parameter "%s" must be defined.', $name));
+        }
+        $this->loadedDynamicParameters[$name] = true;
+
+        return $this->dynamicParameters[$name] = $value;
+    }
+
+    /**
+     * Gets the default parameters.
+     *
+     * @return array An array of the default parameters
+     */
+    protected function getDefaultParameters()
+    {
+        return array(
+            'env(foo)' => '["foo","bar"]',
+            'env(bar)' => 'null',
+        );
+    }
+}