diff --git a/src/Symfony/Component/Ldap/Adapter/ExtLdap/Query.php b/src/Symfony/Component/Ldap/Adapter/ExtLdap/Query.php
index 519357ad4c6a5..63c55330b5a3e 100644
--- a/src/Symfony/Component/Ldap/Adapter/ExtLdap/Query.php
+++ b/src/Symfony/Component/Ldap/Adapter/ExtLdap/Query.php
@@ -24,9 +24,6 @@ class Query extends AbstractQuery
     // As of PHP 7.2, we can use LDAP_CONTROL_PAGEDRESULTS instead of this
     public const PAGINATION_OID = '1.2.840.113556.1.4.319';
 
-    /** @var Connection */
-    protected $connection;
-
     /** @var resource[] */
     private $results;
 
@@ -156,17 +153,13 @@ public function execute()
      * Returns an LDAP search resource. If this query resulted in multiple searches, only the first
      * page will be returned.
      *
-     * @return resource
+     * @return resource|null
      *
      * @internal
      */
     public function getResource(int $idx = 0)
     {
-        if (null === $this->results || $idx >= \count($this->results)) {
-            return null;
-        }
-
-        return $this->results[$idx];
+        return $this->results[$idx] ?? null;
     }
 
     /**
@@ -259,9 +252,9 @@ private function controlPagedResultResponse($con, $result, string $cookie = ''):
      *
      * @param resource $con
      *
-     * @return resource
+     * @return resource|false
      */
-    private function callSearchFunction($con, string $func, int $sizeLimit)
+    private function callSearchFunction($con, callable $func, int $sizeLimit)
     {
         if (\PHP_VERSION_ID < 70300) {
             return @$func($con, $this->dn, $this->query, $this->options['filter'], $this->options['attrsOnly'], $sizeLimit, $this->options['timeout'], $this->options['deref']);
diff --git a/src/Symfony/Component/Ldap/Adapter/ExtLdap/UpdateOperation.php b/src/Symfony/Component/Ldap/Adapter/ExtLdap/UpdateOperation.php
index 4ef536efc689c..cb57c1d6296ea 100644
--- a/src/Symfony/Component/Ldap/Adapter/ExtLdap/UpdateOperation.php
+++ b/src/Symfony/Component/Ldap/Adapter/ExtLdap/UpdateOperation.php
@@ -19,7 +19,7 @@ class UpdateOperation
     private $values;
     private $attribute;
 
-    private $validOperationTypes = [
+    private const VALID_OPERATION_TYPES = [
         \LDAP_MODIFY_BATCH_ADD,
         \LDAP_MODIFY_BATCH_REMOVE,
         \LDAP_MODIFY_BATCH_REMOVE_ALL,
@@ -34,7 +34,7 @@ class UpdateOperation
      */
     public function __construct(int $operationType, string $attribute, ?array $values)
     {
-        if (!\in_array($operationType, $this->validOperationTypes, true)) {
+        if (!\in_array($operationType, self::VALID_OPERATION_TYPES, true)) {
             throw new UpdateOperationException(sprintf('"%s" is not a valid modification type.', $operationType));
         }
         if (\LDAP_MODIFY_BATCH_REMOVE_ALL === $operationType && null !== $values) {
diff --git a/src/Symfony/Component/Ldap/Entry.php b/src/Symfony/Component/Ldap/Entry.php
index 71b675aa7006c..51477a5a51a01 100644
--- a/src/Symfony/Component/Ldap/Entry.php
+++ b/src/Symfony/Component/Ldap/Entry.php
@@ -18,14 +18,23 @@
 class Entry
 {
     private $dn;
-    private $attributes;
-    private $lowerMap;
 
+    /**
+     * @var array<string, array>
+     */
+    private $attributes = [];
+
+    /**
+     * @var array<string, string>
+     */
+    private $lowerMap = [];
+
+    /**
+     * @param array<string, array> $attributes
+     */
     public function __construct(string $dn, array $attributes = [])
     {
         $this->dn = $dn;
-        $this->attributes = [];
-        $this->lowerMap = [];
 
         foreach ($attributes as $key => $attribute) {
             $this->setAttribute($key, $attribute);