diff --git a/composer.json b/composer.json
index 78fa537f6..ef2b400df 100644
--- a/composer.json
+++ b/composer.json
@@ -28,10 +28,10 @@
         "composer/semver": "^1.0",
         "composer/spdx-licenses": "^1.0",
         "seld/jsonlint": "^1.4",
-        "symfony/console": "^2.7 || ^3.0",
-        "symfony/finder": "^2.7 || ^3.0",
-        "symfony/process": "^2.7 || ^3.0",
-        "symfony/filesystem": "^2.7 || ^3.0",
+        "symfony/console": "^2.7 || ^3.0 || ^4.0",
+        "symfony/finder": "^2.7 || ^3.0 || ^4.0",
+        "symfony/process": "^2.7 || ^3.0 || ^4.0",
+        "symfony/filesystem": "^2.7 || ^3.0 || ^4.0",
         "seld/phar-utils": "^1.0",
         "seld/cli-prompt": "^1.0",
         "psr/log": "^1.0"
diff --git a/src/Composer/Command/ShowCommand.php b/src/Composer/Command/ShowCommand.php
index e850b96d6..694e23874 100644
--- a/src/Composer/Command/ShowCommand.php
+++ b/src/Composer/Command/ShowCommand.php
@@ -12,32 +12,33 @@
 
 namespace Composer\Command;
 
-use Composer\DependencyResolver\Pool;
+use Composer\Composer;
 use Composer\DependencyResolver\DefaultPolicy;
+use Composer\DependencyResolver\Pool;
 use Composer\Json\JsonFile;
-use Composer\Package\CompletePackageInterface;
-use Composer\Package\Version\VersionParser;
 use Composer\Package\BasePackage;
+use Composer\Package\CompletePackageInterface;
+use Composer\Package\PackageInterface;
+use Composer\Package\Version\VersionParser;
 use Composer\Package\Version\VersionSelector;
 use Composer\Plugin\CommandEvent;
 use Composer\Plugin\PluginEvents;
-use Composer\Package\PackageInterface;
+use Composer\Repository\ArrayRepository;
+use Composer\Repository\ComposerRepository;
+use Composer\Repository\CompositeRepository;
+use Composer\Repository\PlatformRepository;
+use Composer\Repository\RepositoryFactory;
+use Composer\Repository\RepositoryInterface;
 use Composer\Semver\Constraint\ConstraintInterface;
+use Composer\Semver\Semver;
+use Composer\Spdx\SpdxLicenses;
 use Composer\Util\Platform;
 use Symfony\Component\Console\Formatter\OutputFormatterStyle;
-use Symfony\Component\Console\Input\InputInterface;
 use Symfony\Component\Console\Input\InputArgument;
+use Symfony\Component\Console\Input\InputInterface;
 use Symfony\Component\Console\Input\InputOption;
 use Symfony\Component\Console\Output\OutputInterface;
-use Composer\Repository\ArrayRepository;
-use Composer\Repository\CompositeRepository;
-use Composer\Repository\ComposerRepository;
-use Composer\Repository\PlatformRepository;
-use Composer\Repository\RepositoryInterface;
-use Composer\Repository\RepositoryFactory;
-use Composer\Spdx\SpdxLicenses;
-use Composer\Composer;
-use Composer\Semver\Semver;
+use Symfony\Component\Console\Terminal;
 
 /**
  * @author Robert Schönthal <seroscho@googlemail.com>
@@ -255,7 +256,13 @@ EOT
             $packageListFilter = $this->getRootRequires();
         }
 
-        list($width) = $this->getApplication()->getTerminalDimensions();
+        if (class_exists('Symfony\Component\Console\Terminal')) {
+            $terminal = new Terminal();
+            $width = $terminal->getWidth();
+        } else {
+            // For versions of Symfony console before 3.2
+            list($width) = $this->getApplication()->getTerminalDimensions();
+        }
         if (null === $width) {
             // In case the width is not detected, we're probably running the command
             // outside of a real terminal, use space without a limit
diff --git a/src/Composer/IO/ConsoleIO.php b/src/Composer/IO/ConsoleIO.php
index acb8a8564..f3a99edf2 100644
--- a/src/Composer/IO/ConsoleIO.php
+++ b/src/Composer/IO/ConsoleIO.php
@@ -12,11 +12,12 @@
 
 namespace Composer\IO;
 
+use Composer\Question\StrictConfirmationQuestion;
+use Symfony\Component\Console\Helper\HelperSet;
 use Symfony\Component\Console\Input\InputInterface;
 use Symfony\Component\Console\Output\ConsoleOutputInterface;
 use Symfony\Component\Console\Output\OutputInterface;
-use Symfony\Component\Console\Helper\HelperSet;
-use Composer\Question\StrictConfirmationQuestion;
+use Symfony\Component\Console\Question\ChoiceQuestion;
 use Symfony\Component\Console\Question\Question;
 
 /**
@@ -281,11 +282,14 @@ class ConsoleIO extends BaseIO
      */
     public function select($question, $choices, $default, $attempts = false, $errorMessage = 'Value "%s" is invalid', $multiselect = false)
     {
-        if ($this->isInteractive()) {
-            return $this->helperSet->get('dialog')->select($this->getErrorOutput(), $question, $choices, $default, $attempts, $errorMessage, $multiselect);
-        }
+        /** @var \Symfony\Component\Console\Helper\QuestionHelper $helper */
+        $helper = $this->helperSet->get('question');
+        $question = new ChoiceQuestion($question, $choices, $default);
+        $question->setMaxAttempts($attempts ?: null); // IOInterface requires false, and Question requires null or int
+        $question->setErrorMessage($errorMessage);
+        $question->setMultiselect($multiselect);
 
-        return $default;
+        return $helper->ask($this->input, $this->getErrorOutput(), $question);
     }
 
     /**
diff --git a/src/Composer/Util/ProcessExecutor.php b/src/Composer/Util/ProcessExecutor.php
index 1074b2fce..408aa9eae 100644
--- a/src/Composer/Util/ProcessExecutor.php
+++ b/src/Composer/Util/ProcessExecutor.php
@@ -12,9 +12,9 @@
 
 namespace Composer\Util;
 
+use Composer\IO\IOInterface;
 use Symfony\Component\Process\Process;
 use Symfony\Component\Process\ProcessUtils;
-use Composer\IO\IOInterface;
 
 /**
  * @author Robert Schönthal <seroscho@googlemail.com>
@@ -131,6 +131,59 @@ class ProcessExecutor
      */
     public static function escape($argument)
     {
-        return ProcessUtils::escapeArgument($argument);
+        if (method_exists('Symfony\Component\Process\ProcessUtils', 'escapeArgument')) {
+            return ProcessUtils::escapeArgument($argument);
+        }
+        return self::escapeArgument($argument);
+    }
+
+    /**
+     * Copy of ProcessUtils::escapeArgument() that is removed in Symfony 4.
+     *
+     * @param string $argument
+     *
+     * @return string
+     */
+    private static function escapeArgument($argument)
+    {
+        //Fix for PHP bug #43784 escapeshellarg removes % from given string
+        //Fix for PHP bug #49446 escapeshellarg doesn't work on Windows
+        //@see https://bugs.php.net/bug.php?id=43784
+        //@see https://bugs.php.net/bug.php?id=49446
+        if ('\\' === DIRECTORY_SEPARATOR) {
+            if ('' === $argument) {
+                return escapeshellarg($argument);
+            }
+
+            $escapedArgument = '';
+            $quote = false;
+            foreach (preg_split('/(")/', $argument, -1, PREG_SPLIT_NO_EMPTY | PREG_SPLIT_DELIM_CAPTURE) as $part) {
+                if ('"' === $part) {
+                    $escapedArgument .= '\\"';
+                } elseif (self::isSurroundedBy($part, '%')) {
+                    // Avoid environment variable expansion
+                    $escapedArgument .= '^%"'.substr($part, 1, -1).'"^%';
+                } else {
+                    // escape trailing backslash
+                    if ('\\' === substr($part, -1)) {
+                        $part .= '\\';
+                    }
+                    $quote = true;
+                    $escapedArgument .= $part;
+                }
+            }
+            if ($quote) {
+                $escapedArgument = '"'.$escapedArgument.'"';
+            }
+
+            return $escapedArgument;
+        }
+
+        return "'".str_replace("'", "'\\''", $argument)."'";
+    }
+
+    private static function isSurroundedBy($arg, $char)
+    {
+        return 2 < strlen($arg) && $char === $arg[0] && $char === $arg[strlen($arg) - 1];
     }
 }
diff --git a/tests/Composer/Test/IO/ConsoleIOTest.php b/tests/Composer/Test/IO/ConsoleIOTest.php
index ff96a011f..183012b63 100644
--- a/tests/Composer/Test/IO/ConsoleIOTest.php
+++ b/tests/Composer/Test/IO/ConsoleIOTest.php
@@ -229,27 +229,27 @@ class ConsoleIOTest extends TestCase
     {
         $inputMock = $this->getMock('Symfony\Component\Console\Input\InputInterface');
         $outputMock = $this->getMock('Symfony\Component\Console\Output\OutputInterface');
-        $dialogMock = $this->getMock('Symfony\Component\Console\Helper\DialogHelper');
-        $helperMock = $this->getMock('Symfony\Component\Console\Helper\HelperSet');
+        $helperMock = $this->getMock('Symfony\Component\Console\Helper\QuestionHelper');
+        $setMock = $this->getMock('Symfony\Component\Console\Helper\HelperSet');
 
-        $inputMock->expects($this->once())
-            ->method('isInteractive')
-            ->will($this->returnValue(true));
-        $dialogMock->expects($this->once())
-            ->method('select')
-            ->with($this->isInstanceOf('Symfony\Component\Console\Output\OutputInterface'),
-                $this->equalTo('Select item'),
-                $this->equalTo(array("item1", "item2")),
-                $this->equalTo(null),
-                $this->equalTo(false),
-                $this->equalTo("Error message"),
-                $this->equalTo(true));
-        $helperMock->expects($this->once())
+        $helperMock
+            ->expects($this->once())
+            ->method('ask')
+            ->with(
+                $this->isInstanceOf('Symfony\Component\Console\Input\InputInterface'),
+                $this->isInstanceOf('Symfony\Component\Console\Output\OutputInterface'),
+                $this->isInstanceOf('Symfony\Component\Console\Question\Question')
+            )
+        ;
+
+        $setMock
+            ->expects($this->once())
             ->method('get')
-            ->with($this->equalTo('dialog'))
-            ->will($this->returnValue($dialogMock));
+            ->with($this->equalTo('question'))
+            ->will($this->returnValue($helperMock))
+        ;
 
-        $consoleIO = new ConsoleIO($inputMock, $outputMock, $helperMock);
+        $consoleIO = new ConsoleIO($inputMock, $outputMock, $setMock);
         $consoleIO->select('Select item', array("item1", "item2"), null, false, "Error message", true);
     }
 
diff --git a/tests/Composer/Test/Question/StrictConfirmationQuestionTest.php b/tests/Composer/Test/Question/StrictConfirmationQuestionTest.php
index b0ad8c60a..a69d1aeef 100644
--- a/tests/Composer/Test/Question/StrictConfirmationQuestionTest.php
+++ b/tests/Composer/Test/Question/StrictConfirmationQuestionTest.php
@@ -16,6 +16,8 @@ use Composer\Question\StrictConfirmationQuestion;
 use PHPUnit\Framework\TestCase;
 use Symfony\Component\Console\Exception\InvalidArgumentException;
 use Symfony\Component\Console\Helper\QuestionHelper;
+use Symfony\Component\Console\Input\ArrayInput;
+use Symfony\Component\Console\Input\StreamableInputInterface;
 use Symfony\Component\Console\Output\StreamOutput;
 
 /**
@@ -42,11 +44,11 @@ class StrictConfirmationQuestionTest extends TestCase
      */
     public function testAskConfirmationBadAnswer($answer)
     {
-        $dialog = new QuestionHelper();
-        $dialog->setInputStream($this->getInputStream($answer."\n"));
+        list($input, $dialog) = $this->createInput($answer."\n");
+
         $question = new StrictConfirmationQuestion('Do you like French fries?');
         $question->setMaxAttempts(1);
-        $dialog->ask($this->createInputInterfaceMock(), $this->createOutputInterface(), $question);
+        $dialog->ask($input, $this->createOutputInterface(), $question);
     }
 
     /**
@@ -54,11 +56,10 @@ class StrictConfirmationQuestionTest extends TestCase
      */
     public function testAskConfirmation($question, $expected, $default = true)
     {
-        $dialog = new QuestionHelper();
+        list($input, $dialog) = $this->createInput($question."\n");
 
-        $dialog->setInputStream($this->getInputStream($question."\n"));
         $question = new StrictConfirmationQuestion('Do you like French fries?', $default);
-        $this->assertEquals($expected, $dialog->ask($this->createInputInterfaceMock(), $this->createOutputInterface(), $question), 'confirmation question should '.($expected ? 'pass' : 'cancel'));
+        $this->assertEquals($expected, $dialog->ask($input, $this->createOutputInterface(), $question), 'confirmation question should '.($expected ? 'pass' : 'cancel'));
     }
 
     public function getAskConfirmationData()
@@ -75,13 +76,13 @@ class StrictConfirmationQuestionTest extends TestCase
 
     public function testAskConfirmationWithCustomTrueAndFalseAnswer()
     {
-        $dialog = new QuestionHelper();
-
         $question = new StrictConfirmationQuestion('Do you like French fries?', false, '/^ja$/i', '/^nein$/i');
-        $dialog->setInputStream($this->getInputStream("ja\n"));
-        $this->assertTrue($dialog->ask($this->createInputInterfaceMock(), $this->createOutputInterface(), $question));
-        $dialog->setInputStream($this->getInputStream("nein\n"));
-        $this->assertFalse($dialog->ask($this->createInputInterfaceMock(), $this->createOutputInterface(), $question));
+
+        list($input, $dialog) = $this->createInput("ja\n");
+        $this->assertTrue($dialog->ask($input, $this->createOutputInterface(), $question));
+
+        list($input, $dialog) = $this->createInput("nein\n");
+        $this->assertFalse($dialog->ask($input, $this->createOutputInterface(), $question));
     }
 
     protected function getInputStream($input)
@@ -98,13 +99,19 @@ class StrictConfirmationQuestionTest extends TestCase
         return new StreamOutput(fopen('php://memory', 'r+', false));
     }
 
-    protected function createInputInterfaceMock($interactive = true)
+    protected function createInput($entry)
     {
-        $mock = $this->getMockBuilder('Symfony\Component\Console\Input\InputInterface')->getMock();
-        $mock->expects($this->any())
-            ->method('isInteractive')
-            ->will($this->returnValue($interactive));
+        $stream = $this->getInputStream($entry);
+        $input = new ArrayInput(array('--no-interaction'));
+        $dialog = new QuestionHelper();
 
-        return $mock;
+        if (method_exists($dialog, 'setInputStream')) {
+            $dialog->setInputStream($stream);
+        }
+        if ($input instanceof StreamableInputInterface) {
+            $input->setStream($stream);
+        }
+
+        return array($input, $dialog);
     }
 }