diff --git a/src/JsonSerializer/JsonSerializer.php b/src/JsonSerializer/JsonSerializer.php
index 4b16ea2..f1af960 100644
--- a/src/JsonSerializer/JsonSerializer.php
+++ b/src/JsonSerializer/JsonSerializer.php
@@ -548,7 +548,9 @@ protected function unserializeObject($value)
         foreach ($value as $property => $propertyValue) {
             try {
                 $propRef = $this->getReflectionProperty($ref, $property);
-                $propRef->setAccessible(true);
+                if (version_compare(PHP_VERSION, '8.1.0') < 0) {
+                    $propRef->setAccessible(true);
+                }
                 $propRef->setValue($obj, $this->unserializeData($propertyValue));
             } catch (ReflectionException $e) {
                 switch ($this->undefinedAttributeMode) {