diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index 0d75021..4b70f0b 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -9,7 +9,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        php: ['5.3', '5.4', '5.5', '5.6', '7.0', '7.1', '7.2', '7.3', '7.4', '8.0', '8.1', '8.2']
+        php: ['5.3', '5.4', '5.5', '5.6', '7.0', '7.1', '7.2', '7.3', '7.4', '8.0', '8.1', '8.2', '8.3', '8.4']
 
     steps:
       - uses: actions/checkout@v2
@@ -28,13 +28,7 @@ jobs:
           find src/ tests/ -name '*.php' -print0 | xargs -0 -n1 -P4 php -dxdebug.mode=off -l >/dev/null
 
       - name: Install dependencies
-        if: ${{ matrix.php <= '8.1' }}
         run: composer update
 
-      - name: Install dependencies PHP 8.2
-        # @todo: Needed until prophecy (req by phpunit) allows PHP 8.2, https://github.com/phpspec/prophecy/issues/556
-        if: ${{ matrix.php > '8.1' }}
-        run: composer update --ignore-platform-req=php+
-
       - name: Run test suite
         run: vendor/bin/phpunit
diff --git a/src/ClassAliasMapGenerator.php b/src/ClassAliasMapGenerator.php
index 8c09ee8..cec32f9 100644
--- a/src/ClassAliasMapGenerator.php
+++ b/src/ClassAliasMapGenerator.php
@@ -46,15 +46,12 @@ class ClassAliasMapGenerator
      * @param Composer $composer
      * @param IOInterface $io
      */
-    public function __construct(Composer $composer, IOInterface $io = null, $config = null)
+    public function __construct(Composer $composer, IOInterface $io)
     {
         $this->composer = $composer;
-        $this->io = $io ?: new NullIO();
-        if (\is_bool($config)) {
-            // Happens during upgrade from older versions, so try to be graceful
-            $config = new Config($this->composer->getPackage());
-        }
-        $this->config = $config ?: new Config($this->composer->getPackage());
+        $this->io = $io;
+
+        $this->config = new Config($this->composer->getPackage(), $this->io);
     }
 
     /**
diff --git a/src/Config.php b/src/Config.php
index 8155459..eae777c 100644
--- a/src/Config.php
+++ b/src/Config.php
@@ -39,9 +39,9 @@ class Config
      * @param PackageInterface $package
      * @param IOInterface $io
      */
-    public function __construct(PackageInterface $package, IOInterface $io = null)
+    public function __construct(PackageInterface $package, IOInterface $io)
     {
-        $this->io = $io ?: new NullIO();
+        $this->io = $io;
         $this->setAliasLoaderConfigFromPackage($package);
     }
 
@@ -55,7 +55,7 @@ public function get($configKey)
             throw new \InvalidArgumentException('Configuration key must not be empty', 1444039407);
         }
         // Extract parts of the path
-        $configKey = str_getcsv($configKey, '.');
+        $configKey = str_getcsv($configKey, '.',  '"', '\\');
         // Loop through each part and extract its value
         $value = $this->config;
         foreach ($configKey as $segment) {
diff --git a/src/IncludeFile.php b/src/IncludeFile.php
index 308ad4b..5194d0e 100644
--- a/src/IncludeFile.php
+++ b/src/IncludeFile.php
@@ -46,14 +46,13 @@ class IncludeFile
      * @param IOInterface $io
      * @param Composer $composer
      * @param TokenInterface[] $tokens
-     * @param Filesystem $filesystem
      */
-    public function __construct(IOInterface $io, Composer $composer, array $tokens, Filesystem $filesystem = null)
+    public function __construct(IOInterface $io, Composer $composer, array $tokens)
     {
         $this->io = $io;
         $this->composer = $composer;
         $this->tokens = $tokens;
-        $this->filesystem = $filesystem ?: new Filesystem();
+        $this->filesystem = new Filesystem();
     }
 
     public function register()