diff --git a/.github/workflows/continuous-integration.yml b/.github/workflows/continuous-integration.yml
index 9a7f363dc..9f212844d 100644
--- a/.github/workflows/continuous-integration.yml
+++ b/.github/workflows/continuous-integration.yml
@@ -23,6 +23,7 @@ jobs:
           - "8.2"
           - "8.3"
           - "8.4"
+          - "8.5"
 
     steps:
       - name: Checkout
diff --git a/library/Exceptions/NestedValidationException.php b/library/Exceptions/NestedValidationException.php
index 74fe7689d..4ec37ec54 100644
--- a/library/Exceptions/NestedValidationException.php
+++ b/library/Exceptions/NestedValidationException.php
@@ -113,7 +113,7 @@ public function getIterator(): SplObjectStorage
             $lastDepth = $currentDepth;
             $lastDepthOriginal = $currentDepthOriginal;
 
-            $childrenExceptions->attach($childException, $currentDepth);
+            $childrenExceptions->offsetSet($childException, $currentDepth);
         }
 
         return $childrenExceptions;
diff --git a/library/Factory.php b/library/Factory.php
index 1799eb607..015872dc0 100644
--- a/library/Factory.php
+++ b/library/Factory.php
@@ -246,8 +246,6 @@ private function extractPropertiesValues(Validatable $validatable, ReflectionCla
     {
         $values = [];
         foreach ($reflection->getProperties() as $property) {
-            $property->setAccessible(true);
-
             $propertyValue = $property->getValue($validatable);
             if ($propertyValue === null) {
                 continue;
diff --git a/phpunit.xml.dist b/phpunit.xml.dist
index d0c517214..a18a1bb87 100644
--- a/phpunit.xml.dist
+++ b/phpunit.xml.dist
@@ -4,6 +4,7 @@
          bootstrap="vendor/autoload.php"
          backupGlobals="false"
          backupStaticAttributes="false"
+         convertDeprecationsToExceptions="true"
          convertErrorsToExceptions="true"
          convertNoticesToExceptions="true"
          convertWarningsToExceptions="true"
diff --git a/tests/unit/Rules/EmailTest.php b/tests/unit/Rules/EmailTest.php
index 6f2fbedab..69ad713cb 100644
--- a/tests/unit/Rules/EmailTest.php
+++ b/tests/unit/Rules/EmailTest.php
@@ -99,7 +99,6 @@ private static function sut(): Email
         $rule = new Email();
 
         $reflection = new ReflectionProperty(Email::class, 'validator');
-        $reflection->setAccessible(true);
         $reflection->setValue($rule, null);
 
         return $rule;
diff --git a/tests/unit/Rules/FactorTest.php b/tests/unit/Rules/FactorTest.php
index 78a1c37fd..cc5f02ad6 100644
--- a/tests/unit/Rules/FactorTest.php
+++ b/tests/unit/Rules/FactorTest.php
@@ -18,6 +18,7 @@
 use function uniqid;
 
 use const PHP_INT_MAX;
+use const PHP_VERSION_ID;
 
 /**
  * @group rule
@@ -31,6 +32,32 @@
  */
 final class FactorTest extends RuleTestCase
 {
+    /**
+     * Some edge cases emit E_DEPRECATED on PHP >= 8.5.
+     *
+     * @test
+     *
+     * @dataProvider providerForInvalidInputEdgeCases
+     */
+    public function shouldFailOnInvalidInputEdgeCases(Factor $rule, mixed $input): void
+    {
+        if (PHP_VERSION_ID >= 80500) {
+            $this->markTestSkipped('This test emits E_DEPRECATED on PHP >= 8.5');
+        }
+
+        self::assertInvalidInput($rule, $input);
+    }
+
+    /**
+     * @return array<string, array{0:Factor, 1:mixed}>
+     */
+    public static function providerForInvalidInputEdgeCases(): array
+    {
+        return [
+            'mt_rand is not factor PHP_INT_MAX + 1' => [new Factor(mt_rand()), PHP_INT_MAX + 1],
+        ];
+    }
+
     /**
      * {@inheritDoc}
      */
@@ -93,7 +120,6 @@ public static function providerForInvalidInput(): array
             'mt_rand is not factor 1.5' => [new Factor(mt_rand()), 1.5],
             'mt_rand is not factor -0.5' => [new Factor(mt_rand()), -0.5],
             'mt_rand is not factor -1.5' => [new Factor(mt_rand()), -1.5],
-            'mt_rand is not factor PHP_INT_MAX + 1' => [new Factor(mt_rand()), PHP_INT_MAX + 1],
             'mt_rand is not factor calc' => [new Factor(mt_rand()), mt_rand(1, mt_getrandmax() - 1) / mt_getrandmax()],
             'mt_rand is not factor -calc' => [
                 new Factor(mt_rand()),