diff --git a/src/Apcu.php b/src/Apcu.php
index 13b3fdb..572425b 100644
--- a/src/Apcu.php
+++ b/src/Apcu.php
@@ -59,7 +59,7 @@ final class Apcu extends AbstractAdapter implements
      *
      * @var null|int|float
      */
-    protected $totalSpace;
+    private $totalSpace;
 
     /**
      * Constructor
@@ -731,7 +731,7 @@ protected function internalGetCapabilities()
             );
 
             // update namespace separator on change option
-            $this->getEventManager()->attach('option', function ($event) use ($capabilities, $marker) {
+            $this->getEventManager()->attach('option', static function ($event) use ($capabilities, $marker): void {
                 $params = $event->getParams();
 
                 if (isset($params['namespace_separator'])) {
diff --git a/src/ApcuIterator.php b/src/ApcuIterator.php
index c22329e..9ddf7cc 100644
--- a/src/ApcuIterator.php
+++ b/src/ApcuIterator.php
@@ -5,6 +5,7 @@
 namespace Laminas\Cache\Storage\Adapter;
 
 use APCUIterator as BaseApcuIterator;
+use Laminas\Cache\Storage\Adapter\Apcu;
 use Laminas\Cache\Storage\IteratorInterface;
 use ReturnTypeWillChange;
 
@@ -15,32 +16,25 @@ final class ApcuIterator implements IteratorInterface
 {
     /**
      * The storage instance
-     *
-     * @var Apcu
      */
-    private $storage;
+    private Apcu $storage;
 
     /**
      * The iterator mode
      *
-     * @var int
      * @psalm-var IteratorInterface::CURRENT_AS_*
      */
-    private $mode = IteratorInterface::CURRENT_AS_KEY;
+    private int $mode = IteratorInterface::CURRENT_AS_KEY;
 
     /**
      * The base APCIterator instance
-     *
-     * @var BaseApcuIterator
      */
-    private $baseIterator;
+    private BaseApcuIterator $baseIterator;
 
     /**
      * The length of the namespace prefix
-     *
-     * @var int
      */
-    private $prefixLength;
+    private int $prefixLength;
 
     public function __construct(Apcu $storage, BaseApcuIterator $baseIterator, string $prefix)
     {
diff --git a/test/integration/Psr/CacheItemPool/ApcuIntegrationTest.php b/test/integration/Psr/CacheItemPool/ApcuIntegrationTest.php
index cf46925..d42b290 100644
--- a/test/integration/Psr/CacheItemPool/ApcuIntegrationTest.php
+++ b/test/integration/Psr/CacheItemPool/ApcuIntegrationTest.php
@@ -16,10 +16,8 @@ final class ApcuIntegrationTest extends AbstractCacheItemPoolIntegrationTest
 {
     /**
      * Restore 'apc.use_request_time'
-     *
-     * @var string
      */
-    protected $iniUseRequestTime;
+    private string $iniUseRequestTime;
 
     public function testApcUseRequestTimeThrowsException(): void
     {
diff --git a/test/unit/Apcu/ConfigProviderTest.php b/test/unit/Apcu/ConfigProviderTest.php
index b70c58c..6bf874f 100644
--- a/test/unit/Apcu/ConfigProviderTest.php
+++ b/test/unit/Apcu/ConfigProviderTest.php
@@ -11,8 +11,7 @@
 
 final class ConfigProviderTest extends TestCase
 {
-    /** @var ConfigProvider */
-    private $provider;
+    private ConfigProvider $provider;
 
     protected function setUp(): void
     {
diff --git a/test/unit/Apcu/ModuleTest.php b/test/unit/Apcu/ModuleTest.php
index ef9c72d..42f1a60 100644
--- a/test/unit/Apcu/ModuleTest.php
+++ b/test/unit/Apcu/ModuleTest.php
@@ -10,8 +10,7 @@
 
 final class ModuleTest extends TestCase
 {
-    /** @var Module */
-    private $module;
+    private Module $module;
 
     protected function setUp(): void
     {
diff --git a/test/unit/ApcuTest.php b/test/unit/ApcuTest.php
index 73db946..7db1cc9 100644
--- a/test/unit/ApcuTest.php
+++ b/test/unit/ApcuTest.php
@@ -15,10 +15,8 @@ final class ApcuTest extends AbstractCommonAdapterTest
 {
     /**
      * Restore 'apc.use_request_time'
-     *
-     * @var string
      */
-    protected $iniUseRequestTime;
+    private string $iniUseRequestTime;
 
     public function setUp(): void
     {