diff --git a/src/Symfony/Component/Process/Process.php b/src/Symfony/Component/Process/Process.php
index 99374fef3a..9f6a24933f 100644
--- a/src/Symfony/Component/Process/Process.php
+++ b/src/Symfony/Component/Process/Process.php
@@ -55,7 +55,7 @@ class Process
     private $processInformation;
     private $stdout;
     private $stderr;
-    private $enhanceWindowsCompatibility;
+    private $enhanceWindowsCompatibility = true;
     private $enhanceSigchildCompatibility;
     private $process;
     private $status = self::STATUS_READY;
@@ -146,19 +146,16 @@ class Process
         // on Gnu/Linux, PHP builds with --enable-maintainer-zts are also affected
         // @see : https://bugs.php.net/bug.php?id=51800
         // @see : https://bugs.php.net/bug.php?id=50524
-
         if (null === $this->cwd && (defined('ZEND_THREAD_SAFE') || defined('PHP_WINDOWS_VERSION_BUILD'))) {
             $this->cwd = getcwd();
         }
         if (null !== $env) {
             $this->setEnv($env);
-        } else {
-            $this->env = null;
         }
+
         $this->stdin = $stdin;
         $this->setTimeout($timeout);
         $this->useFileHandles = defined('PHP_WINDOWS_VERSION_BUILD');
-        $this->enhanceWindowsCompatibility = true;
         $this->enhanceSigchildCompatibility = !defined('PHP_WINDOWS_VERSION_BUILD') && $this->isSigchildEnabled();
         $this->options = array_replace(array('suppress_errors' => true, 'binary_pipes' => true), $options);
     }
@@ -1282,7 +1279,7 @@ class Process
     /**
      * Ensures the process is running or terminated, throws a LogicException if the process has a not started.
      *
-     * @param $functionName The function name that was called.
+     * @param string $functionName The function name that was called.
      *
      * @throws LogicException If the process has not run.
      */
@@ -1296,7 +1293,7 @@ class Process
     /**
      * Ensures the process is terminated, throws a LogicException if the process has a status different than `terminated`.
      *
-     * @param $functionName The function name that was called.
+     * @param string $functionName The function name that was called.
      *
      * @throws LogicException If the process is not yet terminated.
      */
diff --git a/src/Symfony/Component/Process/ProcessBuilder.php b/src/Symfony/Component/Process/ProcessBuilder.php
index b6168feb62..c9a77d4482 100644
--- a/src/Symfony/Component/Process/ProcessBuilder.php
+++ b/src/Symfony/Component/Process/ProcessBuilder.php
@@ -30,11 +30,23 @@ class ProcessBuilder
     private $inheritEnv = true;
     private $prefix = array();
 
+    /**
+     * Constructor
+     *
+     * @param string[] $arguments An array of arguments
+     */
     public function __construct(array $arguments = array())
     {
         $this->arguments = $arguments;
     }
 
+    /**
+     * Creates a process builder instance.
+     *
+     * @param string[] $arguments An array of arguments
+     *
+     * @return ProcessBuilder
+     */
     public static function create(array $arguments = array())
     {
         return new static($arguments);
@@ -71,7 +83,12 @@ class ProcessBuilder
     }
 
     /**
-     * @param array $arguments
+     * Sets the arguments of the process.
+     *
+     * Arguments must not be escaped.
+     * Previous arguments are removed.
+     *
+     * @param string[] $arguments
      *
      * @return ProcessBuilder
      */
@@ -82,6 +99,13 @@ class ProcessBuilder
         return $this;
     }
 
+    /**
+     * Sets the working directory.
+     *
+     * @param null|string $cwd The working directory
+     *
+     * @return ProcessBuilder
+     */
     public function setWorkingDirectory($cwd)
     {
         $this->cwd = $cwd;
@@ -89,6 +113,13 @@ class ProcessBuilder
         return $this;
     }
 
+    /**
+     * Sets whether environment variables will be inherited or not.
+     *
+     * @param bool $inheritEnv
+     *
+     * @return ProcessBuilder
+     */
     public function inheritEnvironmentVariables($inheritEnv = true)
     {
         $this->inheritEnv = $inheritEnv;
@@ -96,6 +127,17 @@ class ProcessBuilder
         return $this;
     }
 
+    /**
+     * Sets an environment variable
+     *
+     * Setting a variable overrides its previous value. Use `null` to unset a
+     * defined environment variable.
+     *
+     * @param string      $name  The variable name
+     * @param null|string $value The variable value
+     *
+     * @return ProcessBuilder
+     */
     public function setEnv($name, $value)
     {
         $this->env[$name] = $value;
@@ -110,6 +152,13 @@ class ProcessBuilder
         return $this;
     }
 
+    /**
+     * Sets the input of the process.
+     *
+     * @param string $stdin The input as a string
+     *
+     * @return ProcessBuilder
+     */
     public function setInput($stdin)
     {
         $this->stdin = $stdin;
@@ -147,6 +196,14 @@ class ProcessBuilder
         return $this;
     }
 
+    /**
+     * Adds a proc_open option.
+     *
+     * @param string $name  The option name
+     * @param string $value The option value
+     *
+     * @return ProcessBuilder
+     */
     public function setOption($name, $value)
     {
         $this->options[$name] = $value;
@@ -154,6 +211,13 @@ class ProcessBuilder
         return $this;
     }
 
+    /**
+     * Creates a Process instance and returns it.
+     *
+     * @return Process
+     *
+     * @throws LogicException In case no arguments have been provided
+     */
     public function getProcess()
     {
         if (0 === count($this->prefix) && 0 === count($this->arguments)) {