diff --git a/src/Symfony/Bridge/ProxyManager/LazyProxy/PhpDumper/ProxyDumper.php b/src/Symfony/Bridge/ProxyManager/LazyProxy/PhpDumper/ProxyDumper.php
index 447549b97044..cf9161440178 100644
--- a/src/Symfony/Bridge/ProxyManager/LazyProxy/PhpDumper/ProxyDumper.php
+++ b/src/Symfony/Bridge/ProxyManager/LazyProxy/PhpDumper/ProxyDumper.php
@@ -14,7 +14,6 @@
 use ProxyManager\Generator\ClassGenerator;
 use ProxyManager\GeneratorStrategy\BaseGeneratorStrategy;
 use ProxyManager\ProxyGenerator\LazyLoadingValueHolderGenerator;
-use Symfony\Component\DependencyInjection\Container;
 use Symfony\Component\DependencyInjection\Definition;
 use Symfony\Component\DependencyInjection\LazyProxy\PhpDumper\DumperInterface;
 
@@ -63,7 +62,7 @@ public function isProxyCandidate(Definition $definition)
     /**
      * {@inheritdoc}
      */
-    public function getProxyFactoryCode(Definition $definition, $id)
+    public function getProxyFactoryCode(Definition $definition, $id, $methodName = null)
     {
         $instantiation = 'return';
 
@@ -71,12 +70,10 @@ public function getProxyFactoryCode(Definition $definition, $id)
             $instantiation .= " \$this->services['$id'] =";
         }
 
-        if (func_num_args() >= 3) {
-            $methodName = func_get_arg(2);
-        } else {
-            @trigger_error(sprintf('You must use the third argument of %s to define the method to call to construct your service since version 3.1, not using it won\'t be supported in 4.0.', __METHOD__), E_USER_DEPRECATED);
-            $methodName = 'get'.Container::camelize($id).'Service';
+        if (null === $methodName) {
+            throw new \InvalidArgumentException(sprintf('Missing name of method to call to construct the service "%s".', $id));
         }
+
         $proxyClass = $this->getProxyClassName($definition);
 
         $generatedClass = $this->generateProxyClass($definition);
diff --git a/src/Symfony/Bridge/ProxyManager/Tests/LazyProxy/PhpDumper/ProxyDumperTest.php b/src/Symfony/Bridge/ProxyManager/Tests/LazyProxy/PhpDumper/ProxyDumperTest.php
index 64082c8f7f3f..d4d143a56f7d 100644
--- a/src/Symfony/Bridge/ProxyManager/Tests/LazyProxy/PhpDumper/ProxyDumperTest.php
+++ b/src/Symfony/Bridge/ProxyManager/Tests/LazyProxy/PhpDumper/ProxyDumperTest.php
@@ -80,24 +80,14 @@ public function testGetProxyFactoryCodeWithCustomMethod()
     }
 
     /**
-     * @group legacy
+     * @expectedException \InvalidArgumentException
+     * @expectedExceptionMessage Missing name of method to call to construct the service "foo".
      */
-    public function testGetProxyFactoryCode()
+    public function testGetProxyFactoryCodeWithoutCustomMethod()
     {
         $definition = new Definition(__CLASS__);
-
         $definition->setLazy(true);
-
-        $code = $this->dumper->getProxyFactoryCode($definition, 'foo');
-
-        $this->assertStringMatchesFormat(
-            '%wif ($lazyLoad) {%wreturn $this->services[\'foo\'] =%s'
-            .'SymfonyBridgeProxyManagerTestsLazyProxyPhpDumperProxyDumperTest_%s(%wfunction '
-            .'(&$wrappedInstance, \ProxyManager\Proxy\LazyLoadingInterface $proxy) {'
-            .'%w$wrappedInstance = $this->getFooService(false);%w$proxy->setProxyInitializer(null);'
-            .'%wreturn true;%w}%w);%w}%w',
-            $code
-        );
+        $this->dumper->getProxyFactoryCode($definition, 'foo');
     }
 
     /**
diff --git a/src/Symfony/Component/DependencyInjection/CHANGELOG.md b/src/Symfony/Component/DependencyInjection/CHANGELOG.md
index e95f82b945e7..e7d8baeb4a8c 100644
--- a/src/Symfony/Component/DependencyInjection/CHANGELOG.md
+++ b/src/Symfony/Component/DependencyInjection/CHANGELOG.md
@@ -4,6 +4,8 @@ CHANGELOG
 4.0.0
 -----
 
+ * added a third `$methodName` argument to the `getProxyFactoryCode()` method
+   of the `DumperInterface`
  * removed support for autowiring types
  * removed `Container::isFrozen`
  * removed support for dumping an ucompiled container in `PhpDumper`
diff --git a/src/Symfony/Component/DependencyInjection/LazyProxy/PhpDumper/DumperInterface.php b/src/Symfony/Component/DependencyInjection/LazyProxy/PhpDumper/DumperInterface.php
index ce88eba9742f..9697be53a76d 100644
--- a/src/Symfony/Component/DependencyInjection/LazyProxy/PhpDumper/DumperInterface.php
+++ b/src/Symfony/Component/DependencyInjection/LazyProxy/PhpDumper/DumperInterface.php
@@ -34,11 +34,11 @@ public function isProxyCandidate(Definition $definition);
      *
      * @param Definition $definition
      * @param string     $id         service identifier
-     * @param string     $methodName the method name to get the service, will be added to the interface in 4.0
+     * @param string     $methodName the method name to get the service
      *
      * @return string
      */
-    public function getProxyFactoryCode(Definition $definition, $id/**, $methodName = null */);
+    public function getProxyFactoryCode(Definition $definition, $id, $methodName);
 
     /**
      * Generates the code for the lazy proxy.
diff --git a/src/Symfony/Component/DependencyInjection/Tests/LazyProxy/PhpDumper/NullDumperTest.php b/src/Symfony/Component/DependencyInjection/Tests/LazyProxy/PhpDumper/NullDumperTest.php
index cde2c147e752..1cd8d1a279c0 100644
--- a/src/Symfony/Component/DependencyInjection/Tests/LazyProxy/PhpDumper/NullDumperTest.php
+++ b/src/Symfony/Component/DependencyInjection/Tests/LazyProxy/PhpDumper/NullDumperTest.php
@@ -28,7 +28,7 @@ public function testNullDumper()
         $definition = new Definition('stdClass');
 
         $this->assertFalse($dumper->isProxyCandidate($definition));
-        $this->assertSame('', $dumper->getProxyFactoryCode($definition, 'foo'));
+        $this->assertSame('', $dumper->getProxyFactoryCode($definition, 'foo', 'getFooService'));
         $this->assertSame('', $dumper->getProxyCode($definition));
     }
 }