diff --git a/composer.json b/composer.json
index 8ddd95b..d1733f6 100644
--- a/composer.json
+++ b/composer.json
@@ -47,7 +47,11 @@
     }
   },
   "config": {
-    "sort-packages": true
+    "sort-packages": true,
+    "allow-plugins": {
+      "dealerdirect/phpcodesniffer-composer-installer": true,
+      "phpstan/extension-installer": true
+    }
   },
   "extra": {
     "branch-alias": {
diff --git a/lib/Factory/MetadataFactory.php b/lib/Factory/MetadataFactory.php
index 42c9300..1391351 100644
--- a/lib/Factory/MetadataFactory.php
+++ b/lib/Factory/MetadataFactory.php
@@ -15,11 +15,15 @@ class MetadataFactory extends AbstractMetadataFactory
 {
     /**
      * Metadata object to be created.
+     *
+     * @var class-string<ClassMetadataInterface>
      */
     private string $metadataClass = ClassMetadata::class;
 
     /**
      * Set the metadata class to be created by this factory.
+     *
+     * @param class-string<ClassMetadataInterface> $metadataClass
      */
     public function setMetadataClass(string $metadataClass): void
     {
diff --git a/lib/Loader/FilesLoader.php b/lib/Loader/FilesLoader.php
index ad3a949..c87744f 100644
--- a/lib/Loader/FilesLoader.php
+++ b/lib/Loader/FilesLoader.php
@@ -8,13 +8,13 @@
 
 class FilesLoader extends ChainLoader
 {
-    /** @phpstan-var class-string|null */
+    /** @phpstan-var class-string<LoaderInterface>|null */
     private ?string $loaderClass;
 
     /**
      * {@inheritdoc}
      *
-     * @phpstan-param class-string|null $loaderClass
+     * @phpstan-param class-string<LoaderInterface>|null $loaderClass
      */
     public function __construct(array $paths, ?string $loaderClass = null)
     {
diff --git a/lib/Loader/Processor/ProcessorFactory.php b/lib/Loader/Processor/ProcessorFactory.php
index 326ff78..8345646 100644
--- a/lib/Loader/Processor/ProcessorFactory.php
+++ b/lib/Loader/Processor/ProcessorFactory.php
@@ -25,7 +25,7 @@ class ProcessorFactory implements ProcessorFactoryInterface
 {
     /**
      * @var array<string, string|string[]>
-     * @phpstan-var array<class-string, class-string|class-string[]>
+     * @phpstan-var array<class-string, class-string<ProcessorInterface>|class-string<ProcessorInterface>[]>
      */
     private array $processors = [];
 
@@ -36,7 +36,7 @@ class ProcessorFactory implements ProcessorFactoryInterface
      * Register a processor class for $class.
      *
      * @phpstan-param class-string $class
-     * @phpstan-param class-string $processorClass
+     * @phpstan-param class-string<ProcessorInterface> $processorClass
      */
     public function registerProcessor(string $class, string $processorClass): void
     {
@@ -100,7 +100,7 @@ private function createComposite(array $processors): CompositeProcessor
     }
 
     /**
-     * @phpstan-param class-string $processorClass
+     * @phpstan-param class-string<ProcessorInterface> $processorClass
      */
     private static function instantiateProcessor(string $processorClass): ProcessorInterface // phpcs:ignore SlevomatCodingStandard.Classes.UnusedPrivateElements.UnusedMethod
     {
@@ -115,6 +115,7 @@ public function registerProcessorsByAnnotations(string $dir): void
             ->annotatedBy(Processor::class)
             ->implementationOf(ProcessorInterface::class);
 
+        /** @phpstan-var ReflectionClass<ProcessorInterface> $reflClass */
         foreach ($finder as $reflClass) {
             assert($reflClass instanceof ReflectionClass);
             $annot = $reader->getClassAnnotation($reflClass, Processor::class);
@@ -135,6 +136,7 @@ public function registerProcessorsByAttributes(string $dir): void
             ->withAttribute(Processor::class)
             ->implementationOf(ProcessorInterface::class);
 
+        /** @phpstan-var ReflectionClass<ProcessorInterface> $reflClass */
         foreach ($finder as $reflClass) {
             assert($reflClass instanceof ReflectionClass);
             $attributes = $reflClass->getAttributes(Processor::class);