diff --git a/src/Composer/Console/Application.php b/src/Composer/Console/Application.php
index cd78b595b..c0be8d522 100644
--- a/src/Composer/Console/Application.php
+++ b/src/Composer/Console/Application.php
@@ -66,7 +66,7 @@ class Application extends BaseApplication
     /**
      * @var string Store the initial working directory at startup time
      */
-    private $initialWorkingDirectory = '';
+    private $initialWorkingDirectory;
 
     public function __construct()
     {
diff --git a/src/Composer/Downloader/DownloadManager.php b/src/Composer/Downloader/DownloadManager.php
index 182ce88da..d9aca9bff 100644
--- a/src/Composer/Downloader/DownloadManager.php
+++ b/src/Composer/Downloader/DownloadManager.php
@@ -30,7 +30,7 @@ class DownloadManager
     /** @var bool */
     private $preferDist = false;
     /** @var bool */
-    private $preferSource = false;
+    private $preferSource;
     /** @var array<string, string> */
     private $packagePreferences = array();
     /** @var Filesystem */
diff --git a/src/Composer/Installer.php b/src/Composer/Installer.php
index 535ad8e4c..5280a6451 100644
--- a/src/Composer/Installer.php
+++ b/src/Composer/Installer.php
@@ -145,7 +145,7 @@ class Installer
      * @var array|null
      */
     protected $updateMirrors = false;
-    protected $updateAllowList = null;
+    protected $updateAllowList;
     protected $updateAllowTransitiveDependencies = Request::UPDATE_ONLY_LISTED;
 
     /**
diff --git a/src/Composer/Repository/Vcs/BitbucketDriver.php b/src/Composer/Repository/Vcs/BitbucketDriver.php
index c1781342f..869eeb47f 100644
--- a/src/Composer/Repository/Vcs/BitbucketDriver.php
+++ b/src/Composer/Repository/Vcs/BitbucketDriver.php
@@ -28,7 +28,6 @@ abstract class BitbucketDriver extends VcsDriver
     protected $rootIdentifier;
     protected $tags;
     protected $branches;
-    protected $infoCache = array();
     protected $branchesUrl = '';
     protected $tagsUrl = '';
     protected $homeUrl = '';
diff --git a/src/Composer/Repository/Vcs/FossilDriver.php b/src/Composer/Repository/Vcs/FossilDriver.php
index 491fafa86..5200121bd 100644
--- a/src/Composer/Repository/Vcs/FossilDriver.php
+++ b/src/Composer/Repository/Vcs/FossilDriver.php
@@ -28,7 +28,6 @@ class FossilDriver extends VcsDriver
     protected $rootIdentifier;
     protected $repoFile;
     protected $checkoutDir;
-    protected $infoCache = array();
 
     /**
      * {@inheritDoc}
diff --git a/src/Composer/Repository/Vcs/GitDriver.php b/src/Composer/Repository/Vcs/GitDriver.php
index 230c24303..f6eda648e 100644
--- a/src/Composer/Repository/Vcs/GitDriver.php
+++ b/src/Composer/Repository/Vcs/GitDriver.php
@@ -30,7 +30,6 @@ class GitDriver extends VcsDriver
     protected $branches;
     protected $rootIdentifier;
     protected $repoDir;
-    protected $infoCache = array();
 
     /**
      * {@inheritDoc}
diff --git a/src/Composer/Repository/Vcs/GitHubDriver.php b/src/Composer/Repository/Vcs/GitHubDriver.php
index bbbbd6ecb..e9f80460f 100644
--- a/src/Composer/Repository/Vcs/GitHubDriver.php
+++ b/src/Composer/Repository/Vcs/GitHubDriver.php
@@ -33,7 +33,6 @@ class GitHubDriver extends VcsDriver
     protected $rootIdentifier;
     protected $repoData;
     protected $hasIssues;
-    protected $infoCache = array();
     protected $isPrivate = false;
     private $isArchived = false;
     private $fundingInfo;
diff --git a/src/Composer/Repository/Vcs/HgDriver.php b/src/Composer/Repository/Vcs/HgDriver.php
index 62e3e4a05..4fa737168 100644
--- a/src/Composer/Repository/Vcs/HgDriver.php
+++ b/src/Composer/Repository/Vcs/HgDriver.php
@@ -28,7 +28,6 @@ class HgDriver extends VcsDriver
     protected $branches;
     protected $rootIdentifier;
     protected $repoDir;
-    protected $infoCache = array();
 
     /**
      * {@inheritDoc}
diff --git a/src/Composer/Repository/Vcs/SvnDriver.php b/src/Composer/Repository/Vcs/SvnDriver.php
index 56f1dcfc6..b91f2f603 100644
--- a/src/Composer/Repository/Vcs/SvnDriver.php
+++ b/src/Composer/Repository/Vcs/SvnDriver.php
@@ -36,7 +36,6 @@ class SvnDriver extends VcsDriver
     protected $tags;
     protected $branches;
     protected $rootIdentifier;
-    protected $infoCache = array();
 
     protected $trunkPath = 'trunk';
     protected $branchesPath = 'branches';
diff --git a/src/Composer/Script/Event.php b/src/Composer/Script/Event.php
index 5fab172bf..937dc2f01 100644
--- a/src/Composer/Script/Event.php
+++ b/src/Composer/Script/Event.php
@@ -60,7 +60,6 @@ class Event extends BaseEvent
         $this->composer = $composer;
         $this->io = $io;
         $this->devMode = $devMode;
-        $this->originatingEvent = null;
     }
 
     /**