diff --git a/src/Composer/Repository/FilesystemRepository.php b/src/Composer/Repository/FilesystemRepository.php
index bf2440bc8..71a8fa6fe 100644
--- a/src/Composer/Repository/FilesystemRepository.php
+++ b/src/Composer/Repository/FilesystemRepository.php
@@ -130,20 +130,21 @@ class FilesystemRepository extends WritableArrayRepository
 
         if ($this->dumpVersions) {
             $versions = $this->generateInstalledVersions($installationManager, $installPaths, $devMode, $repoDir);
+            $versionsCode = $this->dumpToPhpCode($versions);
 
-            $fs->filePutContentsIfModified($repoDir.'/installed.php', '<?php return ' . $this->dumpVersion($versions) . ';'."\n");
+            $fs->filePutContentsIfModified($repoDir.'/installed.php', '<?php return ' . $versionsCode . ';'."\n");
             $installedVersionsClass = file_get_contents(__DIR__.'/../InstalledVersions.php');
             // while not strictly needed since https://github.com/composer/composer/pull/9635 - we keep this for BC
             // and overall broader compatibility with people that may not use Composer's ClassLoader. They can
             // simply include InstalledVersions.php manually and have it working in a basic way.
-            $installedVersionsClass = str_replace('public static function initializeInstalled() {}', 'public static function initializeInstalled() {' . PHP_EOL . 'self::$installed = ' . $this->dumpVersion($versions) . ';' . PHP_EOL . '}', $installedVersionsClass);
+            $installedVersionsClass = str_replace('public static function initializeInstalled() {}', 'public static function initializeInstalled() {' . PHP_EOL . 'self::$installed = ' . $versionsCode . ';' . PHP_EOL . '}', $installedVersionsClass);
             $fs->filePutContentsIfModified($repoDir.'/InstalledVersions.php', $installedVersionsClass);
 
             \Composer\InstalledVersions::reload($versions);
         }
     }
 
-    private function dumpVersion(array $array = array(), $level = 0)
+    private function dumpToPhpCode(array $array = array(), $level = 0)
     {
         $lines = "array(\n";
         $level++;
@@ -154,31 +155,26 @@ class FilesystemRepository extends WritableArrayRepository
 
             if (is_array($value)) {
                 if (!empty($value)) {
-                    $lines .= self::dumpVersion($value, $level);
+                    $lines .= $this->dumpToPhpCode($value, $level);
                 } else {
                     $lines .= "array(),\n";
                 }
-            }  elseif (is_null($value)) {
-                $lines .= 'null';
-                $lines .= ",\n";
-            }  elseif (is_bool($value)) {
-                $lines .= $value ? 'true' : 'false';
-                $lines .= ",\n";
+            } elseif ($key === 'install_path') {
+                $lines .= "__DIR__ . " . var_export('/' . $value, true) . ",\n";
             } else {
-                $stringContent = str_replace(array('\\', '\''), array('\\\\', '\\\''), $value);
-                $folder = $key === 'install_path' ? '__DIR__ . DIRECTORY_SEPARATOR . ' : '';
-                $lines .= $folder . "'" . $stringContent . "',\n";
+                $lines .= var_export($value, true) . ",\n";
             }
         }
 
         $lines .= str_repeat('    ', $level - 1) . ')' . ($level - 1 == 0 ? '' : ",\n");
+
         return $lines;
     }
 
     /**
      * @return ?array
      */
-    private function generateInstalledVersions(InstallationManager $installationManager, $installPaths, $devMode, $repoDir)
+    private function generateInstalledVersions(InstallationManager $installationManager, array $installPaths, $devMode, $repoDir)
     {
         if (!$this->dumpVersions) {
             return null;
@@ -207,7 +203,7 @@ class FilesystemRepository extends WritableArrayRepository
                 $reference = ($package->getSourceReference() ?: $package->getDistReference()) ?: null;
             }
 
-            if($package instanceof RootPackageInterface) {
+            if ($package instanceof RootPackageInterface) {
                 $fs = new Filesystem();
                 $to = getcwd();
                 $installPath = $fs->findShortestPath($repoDir, $to, true);
diff --git a/tests/Composer/Test/InstalledVersionsTest.php b/tests/Composer/Test/InstalledVersionsTest.php
index bfd7feb78..80947fc02 100644
--- a/tests/Composer/Test/InstalledVersionsTest.php
+++ b/tests/Composer/Test/InstalledVersionsTest.php
@@ -193,7 +193,7 @@ class InstalledVersionsTest extends TestCase
             'pretty_version' => 'dev-master',
             'version' => 'dev-master',
             'type' => 'library',
-            'install_path' => $this->root . DIRECTORY_SEPARATOR . './',
+            'install_path' => $this->root . '/./',
             'aliases' => array(
                 '1.10.x-dev',
             ),
@@ -243,4 +243,11 @@ class InstalledVersionsTest extends TestCase
 
         $this->assertSame($names, \Composer\InstalledVersions::getInstalledPackagesByType('library'));
     }
+
+    public function testGetInstallPath()
+    {
+        $this->assertSame($this->root . '/./', \Composer\InstalledVersions::getInstallPath('__root__'));
+        $this->assertSame($this->root . '/foo/bar/vendor/woop/woop', \Composer\InstalledVersions::getInstallPath('c/c'));
+        $this->assertNull(\Composer\InstalledVersions::getInstallPath('foo/impl'));
+    }
 }
diff --git a/tests/Composer/Test/Repository/Fixtures/installed.php b/tests/Composer/Test/Repository/Fixtures/installed.php
index 0f6283c7e..a66c75e50 100644
--- a/tests/Composer/Test/Repository/Fixtures/installed.php
+++ b/tests/Composer/Test/Repository/Fixtures/installed.php
@@ -16,7 +16,7 @@ return array(
         'version' => 'dev-master',
         'type' => 'library',
         // @phpstan-ignore-next-line
-        'install_path' => $dir . DIRECTORY_SEPARATOR . './',
+        'install_path' => $dir . '/./',
         'aliases' => array(
             '1.10.x-dev',
         ),
@@ -30,57 +30,57 @@ return array(
             'version' => 'dev-master',
             'type' => 'library',
             // @phpstan-ignore-next-line
-            'install_path' => $dir . DIRECTORY_SEPARATOR . './',
+            'install_path' => $dir . '/./',
             'aliases' => array(
                 '1.10.x-dev',
             ),
             'reference' => 'sourceref-by-default',
-            'dev-requirement' => false,
+            'dev_requirement' => false,
         ),
         'a/provider' => array(
             'pretty_version' => '1.1',
             'version' => '1.1.0.0',
             'type' => 'library',
             // @phpstan-ignore-next-line
-            'install_path' => $dir . DIRECTORY_SEPARATOR . '/foo/bar/vendor/woop/woop',
+            'install_path' => $dir . '/foo/bar/vendor/woop/woop',
             'aliases' => array(),
             'reference' => 'distref-as-no-source',
-            'dev-requirement' => false,
+            'dev_requirement' => false,
         ),
         'a/provider2' => array(
             'pretty_version' => '1.2',
             'version' => '1.2.0.0',
             'type' => 'library',
             // @phpstan-ignore-next-line
-            'install_path' => $dir . DIRECTORY_SEPARATOR . '/foo/bar/vendor/woop/woop',
+            'install_path' => $dir . '/foo/bar/vendor/woop/woop',
             'aliases' => array(
               '1.4',
             ),
             'reference' => 'distref-as-installed-from-dist',
-            'dev-requirement' => false,
+            'dev_requirement' => false,
         ),
         'b/replacer' => array(
             'pretty_version' => '2.2',
             'version' => '2.2.0.0',
             'type' => 'library',
             // @phpstan-ignore-next-line
-            'install_path' => $dir . DIRECTORY_SEPARATOR . '/foo/bar/vendor/woop/woop',
+            'install_path' => $dir . '/foo/bar/vendor/woop/woop',
             'aliases' => array(),
             'reference' => null,
-            'dev-requirement' => false,
+            'dev_requirement' => false,
         ),
         'c/c' => array(
             'pretty_version' => '3.0',
             'version' => '3.0.0.0',
             'type' => 'library',
             // @phpstan-ignore-next-line
-            'install_path' => $dir . DIRECTORY_SEPARATOR . '/foo/bar/vendor/woop/woop',
+            'install_path' => $dir . '/foo/bar/vendor/woop/woop',
             'aliases' => array(),
             'reference' => null,
-            'dev-requirement' => true,
+            'dev_requirement' => true,
         ),
         'foo/impl' => array(
-            'dev-requirement' => false,
+            'dev_requirement' => false,
             'provided' => array(
                 '^1.1',
                 '1.2',
@@ -89,7 +89,7 @@ return array(
             ),
         ),
         'foo/impl2' => array(
-            'dev-requirement' => false,
+            'dev_requirement' => false,
             'provided' => array(
                 '2.0',
             ),
@@ -98,7 +98,7 @@ return array(
             ),
         ),
         'foo/replaced' => array(
-            'dev-requirement' => false,
+            'dev_requirement' => false,
             'replaced' => array(
                 '^3.0',
             ),