diff --git a/src/Composer/Downloader/ArchiveDownloader.php b/src/Composer/Downloader/ArchiveDownloader.php
index bcee49f9a..d77d55738 100644
--- a/src/Composer/Downloader/ArchiveDownloader.php
+++ b/src/Composer/Downloader/ArchiveDownloader.php
@@ -29,14 +29,12 @@ abstract class ArchiveDownloader extends FileDownloader
 {
     public function download(PackageInterface $package, $path, PackageInterface $prevPackage = null, $output = true)
     {
-        $res = parent::download($package, $path, $prevPackage, $output);
-
         // if not downgrading and the dir already exists it seems we have an inconsistent state in the vendor dir and the user should fix it
         if (!$prevPackage && is_dir($path) && !$this->filesystem->isDirEmpty($path)) {
             throw new IrrecoverableDownloadException('Expected empty path to extract '.$package.' into but directory exists: '.$path);
         }
 
-        return $res;
+        return parent::download($package, $path, $prevPackage, $output);
     }
 
     /**
diff --git a/src/Composer/Downloader/FileDownloader.php b/src/Composer/Downloader/FileDownloader.php
index f5674cf90..5f88cf140 100644
--- a/src/Composer/Downloader/FileDownloader.php
+++ b/src/Composer/Downloader/FileDownloader.php
@@ -27,7 +27,9 @@ use Composer\EventDispatcher\EventDispatcher;
 use Composer\Util\Filesystem;
 use Composer\Util\HttpDownloader;
 use Composer\Util\Url as UrlUtil;
+use Composer\Util\ProcessExecutor;
 use Composer\Downloader\TransportException;
+use React\Promise\PromiseInterface;
 
 /**
  * Base downloader for files
@@ -51,6 +53,8 @@ class FileDownloader implements DownloaderInterface, ChangeReportInterface
     protected $cache;
     /** @var EventDispatcher */
     protected $eventDispatcher;
+    /** @var ProcessExecutor */
+    protected $process;
     /**
      * @private this is only public for php 5.3 support in closures
      */
@@ -67,14 +71,15 @@ class FileDownloader implements DownloaderInterface, ChangeReportInterface
      * @param Cache            $cache           Cache instance
      * @param Filesystem       $filesystem      The filesystem
      */
-    public function __construct(IOInterface $io, Config $config, HttpDownloader $httpDownloader, EventDispatcher $eventDispatcher = null, Cache $cache = null, Filesystem $filesystem = null)
+    public function __construct(IOInterface $io, Config $config, HttpDownloader $httpDownloader, EventDispatcher $eventDispatcher = null, Cache $cache = null, Filesystem $filesystem = null, ProcessExecutor $process = null)
     {
         $this->io = $io;
         $this->config = $config;
         $this->eventDispatcher = $eventDispatcher;
         $this->httpDownloader = $httpDownloader;
-        $this->filesystem = $filesystem ?: new Filesystem();
         $this->cache = $cache;
+        $this->process = $process ?: new ProcessExecutor($io);
+        $this->filesystem = $filesystem ?: new Filesystem($this->process);
 
         if ($this->cache && $this->cache->gcIsNecessary()) {
             $this->cache->gc($config->get('cache-files-ttl'), $config->get('cache-files-maxsize'));
@@ -333,10 +338,19 @@ class FileDownloader implements DownloaderInterface, ChangeReportInterface
         $actionName = VersionParser::isUpgrade($initial->getVersion(), $target->getVersion()) ? 'Upgrading' : 'Downgrading';
         $this->io->writeError("  - " . $actionName . " <info>" . $name . "</info> (<comment>" . $from . "</comment> => <comment>" . $to . "</comment>): ", false);
 
-        $this->remove($initial, $path, false);
-        $this->install($target, $path, false);
+        $promise = $this->remove($initial, $path, false);
+        if (!$promise instanceof PromiseInterface) {
+            $promise = \React\Promise\resolve();
+        }
+        $self = $this;
+        $io = $this->io;
+
+        return $promise->then(function () use ($self, $target, $path, $io) {
+            $promise = $self->install($target, $path, false);
+            $io->writeError('');
 
-        $this->io->writeError('');
+            return $promise;
+        });
     }
 
     /**
@@ -410,9 +424,10 @@ class FileDownloader implements DownloaderInterface, ChangeReportInterface
         $output = '';
 
         try {
-            $res = $this->download($package, $targetDir.'_compare', null, false);
+            $this->download($package, $targetDir.'_compare', null, false);
             $this->httpDownloader->wait();
-            $res = $this->install($package, $targetDir.'_compare', false);
+            $this->install($package, $targetDir.'_compare', false);
+            $this->process->wait();
 
             $comparer = new Comparer();
             $comparer->setSource($targetDir.'_compare');
diff --git a/src/Composer/Downloader/GzipDownloader.php b/src/Composer/Downloader/GzipDownloader.php
index 0b12b4380..3ebff597a 100644
--- a/src/Composer/Downloader/GzipDownloader.php
+++ b/src/Composer/Downloader/GzipDownloader.php
@@ -29,15 +29,6 @@ use Composer\Util\Filesystem;
  */
 class GzipDownloader extends ArchiveDownloader
 {
-    /** @var ProcessExecutor */
-    protected $process;
-
-    public function __construct(IOInterface $io, Config $config, HttpDownloader $downloader, EventDispatcher $eventDispatcher = null, Cache $cache = null, Filesystem $fs = null, ProcessExecutor $process = null)
-    {
-        $this->process = $process ?: new ProcessExecutor($io);
-        parent::__construct($io, $config, $downloader, $eventDispatcher, $cache, $fs);
-    }
-
     protected function extract(PackageInterface $package, $file, $path)
     {
         $filename = pathinfo(parse_url($package->getDistUrl(), PHP_URL_PATH), PATHINFO_FILENAME);
diff --git a/src/Composer/Downloader/PathDownloader.php b/src/Composer/Downloader/PathDownloader.php
index 51e9f7709..2cb74d641 100644
--- a/src/Composer/Downloader/PathDownloader.php
+++ b/src/Composer/Downloader/PathDownloader.php
@@ -39,15 +39,6 @@ class PathDownloader extends FileDownloader implements VcsCapableDownloaderInter
     const STRATEGY_SYMLINK = 10;
     const STRATEGY_MIRROR = 20;
 
-    /** @var ProcessExecutor */
-    private $process;
-
-    public function __construct(IOInterface $io, Config $config, HttpDownloader $downloader, EventDispatcher $eventDispatcher = null, Cache $cache = null, Filesystem $fs = null, ProcessExecutor $process = null)
-    {
-        $this->process = $process ?: new ProcessExecutor($io);
-        parent::__construct($io, $config, $downloader, $eventDispatcher, $cache, $fs);
-    }
-
     /**
      * {@inheritdoc}
      */
diff --git a/src/Composer/Downloader/RarDownloader.php b/src/Composer/Downloader/RarDownloader.php
index 0ca15de1f..b0484b661 100644
--- a/src/Composer/Downloader/RarDownloader.php
+++ b/src/Composer/Downloader/RarDownloader.php
@@ -33,15 +33,6 @@ use RarArchive;
  */
 class RarDownloader extends ArchiveDownloader
 {
-    /** @var ProcessExecutor */
-    protected $process;
-
-    public function __construct(IOInterface $io, Config $config, HttpDownloader $downloader, EventDispatcher $eventDispatcher = null, Cache $cache = null, Filesystem $fs = null, ProcessExecutor $process = null)
-    {
-        $this->process = $process ?: new ProcessExecutor($io);
-        parent::__construct($io, $config, $downloader, $eventDispatcher, $cache, $fs);
-    }
-
     protected function extract(PackageInterface $package, $file, $path)
     {
         $processError = null;
diff --git a/src/Composer/Downloader/XzDownloader.php b/src/Composer/Downloader/XzDownloader.php
index 34956d997..b043af333 100644
--- a/src/Composer/Downloader/XzDownloader.php
+++ b/src/Composer/Downloader/XzDownloader.php
@@ -29,16 +29,6 @@ use Composer\Util\Filesystem;
  */
 class XzDownloader extends ArchiveDownloader
 {
-    /** @var ProcessExecutor */
-    protected $process;
-
-    public function __construct(IOInterface $io, Config $config, HttpDownloader $downloader, EventDispatcher $eventDispatcher = null, Cache $cache = null, Filesystem $fs = null, ProcessExecutor $process = null)
-    {
-        $this->process = $process ?: new ProcessExecutor($io);
-
-        parent::__construct($io, $config, $downloader, $eventDispatcher, $cache, $fs);
-    }
-
     protected function extract(PackageInterface $package, $file, $path)
     {
         $command = 'tar -xJf ' . ProcessExecutor::escape($file) . ' -C ' . ProcessExecutor::escape($path);
diff --git a/src/Composer/Downloader/ZipDownloader.php b/src/Composer/Downloader/ZipDownloader.php
index c5fd2b11b..d891fb33b 100644
--- a/src/Composer/Downloader/ZipDownloader.php
+++ b/src/Composer/Downloader/ZipDownloader.php
@@ -34,17 +34,9 @@ class ZipDownloader extends ArchiveDownloader
     private static $hasZipArchive;
     private static $isWindows;
 
-    /** @var ProcessExecutor */
-    protected $process;
     /** @var ZipArchive|null */
     private $zipArchiveObject;
 
-    public function __construct(IOInterface $io, Config $config, HttpDownloader $downloader, EventDispatcher $eventDispatcher = null, Cache $cache = null, Filesystem $fs = null, ProcessExecutor $process = null)
-    {
-        $this->process = $process ?: new ProcessExecutor($io);
-        parent::__construct($io, $config, $downloader, $eventDispatcher, $cache, $fs);
-    }
-
     /**
      * {@inheritDoc}
      */
diff --git a/src/Composer/Factory.php b/src/Composer/Factory.php
index 5bc41ee6b..509fa62b0 100644
--- a/src/Composer/Factory.php
+++ b/src/Composer/Factory.php
@@ -495,11 +495,11 @@ class Factory
         $dm->setDownloader('perforce', new Downloader\PerforceDownloader($io, $config, $process, $fs));
         $dm->setDownloader('zip', new Downloader\ZipDownloader($io, $config, $httpDownloader, $eventDispatcher, $cache, $fs, $process));
         $dm->setDownloader('rar', new Downloader\RarDownloader($io, $config, $httpDownloader, $eventDispatcher, $cache, $fs, $process));
-        $dm->setDownloader('tar', new Downloader\TarDownloader($io, $config, $httpDownloader, $eventDispatcher, $cache, $fs));
+        $dm->setDownloader('tar', new Downloader\TarDownloader($io, $config, $httpDownloader, $eventDispatcher, $cache, $fs, $process));
         $dm->setDownloader('gzip', new Downloader\GzipDownloader($io, $config, $httpDownloader, $eventDispatcher, $cache, $fs, $process));
         $dm->setDownloader('xz', new Downloader\XzDownloader($io, $config, $httpDownloader, $eventDispatcher, $cache, $fs, $process));
-        $dm->setDownloader('phar', new Downloader\PharDownloader($io, $config, $httpDownloader, $eventDispatcher, $cache, $fs));
-        $dm->setDownloader('file', new Downloader\FileDownloader($io, $config, $httpDownloader, $eventDispatcher, $cache, $fs));
+        $dm->setDownloader('phar', new Downloader\PharDownloader($io, $config, $httpDownloader, $eventDispatcher, $cache, $fs, $process));
+        $dm->setDownloader('file', new Downloader\FileDownloader($io, $config, $httpDownloader, $eventDispatcher, $cache, $fs, $process));
         $dm->setDownloader('path', new Downloader\PathDownloader($io, $config, $httpDownloader, $eventDispatcher, $cache, $fs, $process));
 
         return $dm;