diff --git a/src/Symfony/Component/Cache/Adapter/ArrayAdapter.php b/src/Symfony/Component/Cache/Adapter/ArrayAdapter.php
index 3bacde1c16..2898ba50cd 100644
--- a/src/Symfony/Component/Cache/Adapter/ArrayAdapter.php
+++ b/src/Symfony/Component/Cache/Adapter/ArrayAdapter.php
@@ -64,7 +64,7 @@ class ArrayAdapter implements AdapterInterface, LoggerAwareInterface
             } elseif ('b:0;' === $value = $this->values[$key]) {
                 $value = false;
             } elseif (false === $value = unserialize($value)) {
-                $value = null;
+                $this->values[$key] = $value = null;
                 $isHit = false;
             }
         } catch (\Exception $e) {
@@ -210,7 +210,7 @@ class ArrayAdapter implements AdapterInterface, LoggerAwareInterface
                 } elseif ('b:0;' === $value = $this->values[$key]) {
                     $value = false;
                 } elseif (false === $value = unserialize($value)) {
-                    $value = null;
+                    $this->values[$key] = $value = null;
                     $isHit = false;
                 }
             } catch (\Exception $e) {
diff --git a/src/Symfony/Component/Cache/Adapter/PhpFilesAdapter.php b/src/Symfony/Component/Cache/Adapter/PhpFilesAdapter.php
index d39aa9eb39..d2591c1fb0 100644
--- a/src/Symfony/Component/Cache/Adapter/PhpFilesAdapter.php
+++ b/src/Symfony/Component/Cache/Adapter/PhpFilesAdapter.php
@@ -70,7 +70,7 @@ class PhpFilesAdapter extends AbstractAdapter
             if ('N;' === $value) {
                 $values[$id] = null;
             } elseif (is_string($value) && isset($value[2]) && ':' === $value[1]) {
-                $values[$id] = unserialize($value);
+                $values[$id] = parent::unserialize($value);
             }
         }
 
@@ -98,7 +98,7 @@ class PhpFilesAdapter extends AbstractAdapter
                 $value = serialize($value);
             } elseif (is_array($value)) {
                 $serialized = serialize($value);
-                $unserialized = unserialize($serialized);
+                $unserialized = parent::unserialize($serialized);
                 // Store arrays serialized if they contain any objects or references
                 if ($unserialized !== $value || (false !== strpos($serialized, ';R:') && preg_match('/;R:[1-9]/', $serialized))) {
                     $value = $serialized;