diff --git a/src/Symfony/Bundle/FrameworkBundle/Tests/Functional/app/AppKernel.php b/src/Symfony/Bundle/FrameworkBundle/Tests/Functional/app/AppKernel.php
index 12747e6dc2..30bfc56a11 100644
--- a/src/Symfony/Bundle/FrameworkBundle/Tests/Functional/app/AppKernel.php
+++ b/src/Symfony/Bundle/FrameworkBundle/Tests/Functional/app/AppKernel.php
@@ -105,7 +105,8 @@ class AppKernel extends Kernel
 
     public function unserialize($str)
     {
-        call_user_func_array(array($this, '__construct'), unserialize($str));
+        $a = unserialize($str);
+        $this->__construct($a[0], $a[1], $a[2], $a[3]);
     }
 
     protected function getKernelParameters()
diff --git a/src/Symfony/Bundle/SecurityBundle/Tests/Functional/app/AppKernel.php b/src/Symfony/Bundle/SecurityBundle/Tests/Functional/app/AppKernel.php
index 57816ccef9..dfce6e4a6c 100644
--- a/src/Symfony/Bundle/SecurityBundle/Tests/Functional/app/AppKernel.php
+++ b/src/Symfony/Bundle/SecurityBundle/Tests/Functional/app/AppKernel.php
@@ -105,7 +105,8 @@ class AppKernel extends Kernel
 
     public function unserialize($str)
     {
-        call_user_func_array(array($this, '__construct'), unserialize($str));
+        $a = unserialize($str);
+        $this->__construct($a[0], $a[1], $a[2], $a[3]);
     }
 
     protected function getKernelParameters()
diff --git a/src/Symfony/Component/Config/Definition/Builder/ExprBuilder.php b/src/Symfony/Component/Config/Definition/Builder/ExprBuilder.php
index 7cbddc6cf3..885863bbb6 100644
--- a/src/Symfony/Component/Config/Definition/Builder/ExprBuilder.php
+++ b/src/Symfony/Component/Config/Definition/Builder/ExprBuilder.php
@@ -225,8 +225,10 @@ class ExprBuilder
     {
         foreach ($expressions as $k => $expr) {
             if ($expr instanceof ExprBuilder) {
-                $expressions[$k] = function ($v) use ($expr) {
-                    return call_user_func($expr->ifPart, $v) ? call_user_func($expr->thenPart, $v) : $v;
+                $if = $expr->ifPart;
+                $then = $expr->thenPart;
+                $expressions[$k] = function ($v) use ($if, $then) {
+                    return $if($v) ? $then($v) : $v;
                 };
             }
         }
diff --git a/src/Symfony/Component/Config/Definition/VariableNode.php b/src/Symfony/Component/Config/Definition/VariableNode.php
index 6d89e49df5..a19dd58bf8 100644
--- a/src/Symfony/Component/Config/Definition/VariableNode.php
+++ b/src/Symfony/Component/Config/Definition/VariableNode.php
@@ -49,7 +49,9 @@ class VariableNode extends BaseNode implements PrototypeNodeInterface
      */
     public function getDefaultValue()
     {
-        return $this->defaultValue instanceof \Closure ? call_user_func($this->defaultValue) : $this->defaultValue;
+        $v = $this->defaultValue;
+
+        return $v instanceof \Closure ? $v() : $v;
     }
 
     /**
diff --git a/src/Symfony/Component/Config/Exception/FileLoaderImportCircularReferenceException.php b/src/Symfony/Component/Config/Exception/FileLoaderImportCircularReferenceException.php
index b1ad4420dc..6a3b01cfbe 100644
--- a/src/Symfony/Component/Config/Exception/FileLoaderImportCircularReferenceException.php
+++ b/src/Symfony/Component/Config/Exception/FileLoaderImportCircularReferenceException.php
@@ -22,6 +22,6 @@ class FileLoaderImportCircularReferenceException extends FileLoaderLoadException
     {
         $message = sprintf('Circular reference detected in "%s" ("%s" > "%s").', $this->varToString($resources[0]), implode('" > "', $resources), $resources[0]);
 
-        call_user_func('Exception::__construct', $message, $code, $previous);
+        \Exception::__construct($message, $code, $previous);
     }
 }
diff --git a/src/Symfony/Component/Finder/Shell/Command.php b/src/Symfony/Component/Finder/Shell/Command.php
index de701ab4e8..7fcb303004 100644
--- a/src/Symfony/Component/Finder/Shell/Command.php
+++ b/src/Symfony/Component/Finder/Shell/Command.php
@@ -248,14 +248,14 @@ class Command
      */
     public function execute()
     {
-        if (null === $this->errorHandler) {
+        if (null === $errorHandler = $this->errorHandler) {
             exec($this->join(), $output);
         } else {
             $process = proc_open($this->join(), array(0 => array('pipe', 'r'), 1 => array('pipe', 'w'), 2 => array('pipe', 'w')), $pipes);
             $output = preg_split('~(\r\n|\r|\n)~', stream_get_contents($pipes[1]), -1, PREG_SPLIT_NO_EMPTY);
 
             if ($error = stream_get_contents($pipes[2])) {
-                call_user_func($this->errorHandler, $error);
+                $errorHandler($error);
             }
 
             proc_close($process);
diff --git a/src/Symfony/Component/HttpKernel/Tests/HttpCache/TestHttpKernel.php b/src/Symfony/Component/HttpKernel/Tests/HttpCache/TestHttpKernel.php
index cf23d7bf8a..f84d67a0c7 100644
--- a/src/Symfony/Component/HttpKernel/Tests/HttpCache/TestHttpKernel.php
+++ b/src/Symfony/Component/HttpKernel/Tests/HttpCache/TestHttpKernel.php
@@ -74,8 +74,8 @@ class TestHttpKernel extends HttpKernel implements ControllerResolverInterface
 
         $response = new Response($this->body, $this->status, $this->headers);
 
-        if (null !== $this->customizer) {
-            call_user_func($this->customizer, $request, $response);
+        if (null !== $customizer = $this->customizer) {
+            $customizer($request, $response);
         }
 
         return $response;
diff --git a/src/Symfony/Component/Process/Process.php b/src/Symfony/Component/Process/Process.php
index 908a126ffa..e163ab8665 100644
--- a/src/Symfony/Component/Process/Process.php
+++ b/src/Symfony/Component/Process/Process.php
@@ -1102,11 +1102,12 @@ class Process
             $result = $this->processPipes->read($blocking);
         }
 
+        $callback = $this->callback;
         foreach ($result as $type => $data) {
             if (3 == $type) {
                 $this->fallbackExitcode = (int) $data;
             } else {
-                call_user_func($this->callback, $type === self::STDOUT ? self::OUT : self::ERR, $data);
+                $callback($type === self::STDOUT ? self::OUT : self::ERR, $data);
             }
         }
     }
diff --git a/src/Symfony/Component/Process/Tests/AbstractProcessTest.php b/src/Symfony/Component/Process/Tests/AbstractProcessTest.php
index 5689d34067..2a9e9033d1 100644
--- a/src/Symfony/Component/Process/Tests/AbstractProcessTest.php
+++ b/src/Symfony/Component/Process/Tests/AbstractProcessTest.php
@@ -747,7 +747,7 @@ abstract class AbstractProcessTest extends \PHPUnit_Framework_TestCase
     {
         $process = $this->getProcess('php -m');
         $this->setExpectedException('Symfony\Component\Process\Exception\LogicException', sprintf('Process must be started before calling %s.', $method));
-        call_user_func(array($process, $method));
+        $process->{$method}();
     }
 
     public function provideMethodsThatNeedARunningProcess()
@@ -769,7 +769,7 @@ abstract class AbstractProcessTest extends \PHPUnit_Framework_TestCase
         $process = $this->getProcess('php -r "sleep(1);"');
         $process->start();
         try {
-            call_user_func(array($process, $method));
+            $process->{$method}();
             $process->stop(0);
             $this->fail('A LogicException must have been thrown');
         } catch (\Exception $e) {
diff --git a/src/Symfony/Component/Routing/Loader/ClosureLoader.php b/src/Symfony/Component/Routing/Loader/ClosureLoader.php
index 8212c2916d..9edab1e9e3 100644
--- a/src/Symfony/Component/Routing/Loader/ClosureLoader.php
+++ b/src/Symfony/Component/Routing/Loader/ClosureLoader.php
@@ -37,7 +37,7 @@ class ClosureLoader extends Loader
      */
     public function load($closure, $type = null)
     {
-        return call_user_func($closure);
+        return $closure();
     }
 
     /**
diff --git a/src/Symfony/Component/Validator/Constraints/CallbackValidator.php b/src/Symfony/Component/Validator/Constraints/CallbackValidator.php
index ca5a42bca0..32b20e8a50 100644
--- a/src/Symfony/Component/Validator/Constraints/CallbackValidator.php
+++ b/src/Symfony/Component/Validator/Constraints/CallbackValidator.php
@@ -43,7 +43,9 @@ class CallbackValidator extends ConstraintValidator
         $methods = $constraint->methods;
 
         foreach ($methods as $method) {
-            if (is_array($method) || $method instanceof \Closure) {
+            if ($method instanceof \Closure) {
+                $method($object, $this->context);
+            } elseif (is_array($method)) {
                 if (!is_callable($method)) {
                     throw new ConstraintDefinitionException(sprintf('"%s::%s" targeted by Callback constraint is not a valid callable', $method[0], $method[1]));
                 }
diff --git a/src/Symfony/Component/Validator/Constraints/ChoiceValidator.php b/src/Symfony/Component/Validator/Constraints/ChoiceValidator.php
index 93f13c75da..0581d7da74 100644
--- a/src/Symfony/Component/Validator/Constraints/ChoiceValidator.php
+++ b/src/Symfony/Component/Validator/Constraints/ChoiceValidator.php
@@ -45,13 +45,12 @@ class ChoiceValidator extends ConstraintValidator
         }
 
         if ($constraint->callback) {
-            if (is_callable(array($this->context->getClassName(), $constraint->callback))) {
-                $choices = call_user_func(array($this->context->getClassName(), $constraint->callback));
-            } elseif (is_callable($constraint->callback)) {
-                $choices = call_user_func($constraint->callback);
-            } else {
+            if (!is_callable($choices = array($this->context->getClassName(), $constraint->callback))
+                && !is_callable($choices = $constraint->callback)
+            ) {
                 throw new ConstraintDefinitionException('The Choice constraint expects a valid callback');
             }
+            $choices = call_user_func($choices);
         } else {
             $choices = $constraint->choices;
         }
diff --git a/src/Symfony/Component/Validator/Constraints/TypeValidator.php b/src/Symfony/Component/Validator/Constraints/TypeValidator.php
index b89b5cba1d..979df4ec67 100644
--- a/src/Symfony/Component/Validator/Constraints/TypeValidator.php
+++ b/src/Symfony/Component/Validator/Constraints/TypeValidator.php
@@ -35,9 +35,9 @@ class TypeValidator extends ConstraintValidator
         $isFunction = 'is_'.$type;
         $ctypeFunction = 'ctype_'.$type;
 
-        if (function_exists($isFunction) && call_user_func($isFunction, $value)) {
+        if (function_exists($isFunction) && $isFunction($value)) {
             return;
-        } elseif (function_exists($ctypeFunction) && call_user_func($ctypeFunction, $value)) {
+        } elseif (function_exists($ctypeFunction) && $ctypeFunction($value)) {
             return;
         } elseif ($value instanceof $constraint->type) {
             return;