diff --git a/src/Symfony/Bundle/SecurityBundle/Resources/config/collectors.xml b/src/Symfony/Bundle/SecurityBundle/Resources/config/collectors.xml
index 738455358b..de157d5182 100644
--- a/src/Symfony/Bundle/SecurityBundle/Resources/config/collectors.xml
+++ b/src/Symfony/Bundle/SecurityBundle/Resources/config/collectors.xml
@@ -10,7 +10,7 @@
             <argument type="service" id="security.token_storage" on-invalid="ignore" />
             <argument type="service" id="security.role_hierarchy" />
             <argument type="service" id="security.logout_url_generator" />
-            <argument type="service" id="debug.security.access.decision_manager" />
+            <argument type="service" id="security.access.decision_manager" />
         </service>
     </services>
 </container>
diff --git a/src/Symfony/Bundle/SecurityBundle/Resources/config/security_debug.xml b/src/Symfony/Bundle/SecurityBundle/Resources/config/security_debug.xml
index 4312d74741..eb22cbddf5 100644
--- a/src/Symfony/Bundle/SecurityBundle/Resources/config/security_debug.xml
+++ b/src/Symfony/Bundle/SecurityBundle/Resources/config/security_debug.xml
@@ -1,8 +1,8 @@
 <?xml version="1.0" ?>
 
 <container xmlns="http://symfony.com/schema/dic/services"
-    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
-    xsi:schemaLocation="http://symfony.com/schema/dic/services http://symfony.com/schema/dic/services/services-1.0.xsd">
+           xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+           xsi:schemaLocation="http://symfony.com/schema/dic/services http://symfony.com/schema/dic/services/services-1.0.xsd">
 
     <services>
         <service id="debug.security.access.decision_manager" class="Symfony\Component\Security\Core\Authorization\DebugAccessDecisionManager" decorates="security.access.decision_manager" public="false">
diff --git a/src/Symfony/Bundle/SecurityBundle/composer.json b/src/Symfony/Bundle/SecurityBundle/composer.json
index 6e22dc9192..a67980b643 100644
--- a/src/Symfony/Bundle/SecurityBundle/composer.json
+++ b/src/Symfony/Bundle/SecurityBundle/composer.json
@@ -17,7 +17,7 @@
     ],
     "require": {
         "php": ">=5.5.9",
-        "symfony/security": "~3.1",
+        "symfony/security": "~3.1,>=3.1.2",
         "symfony/http-kernel": "~2.8|~3.0",
         "symfony/polyfill-php70": "~1.0"
     },
diff --git a/src/Symfony/Component/Security/Core/Authorization/DebugAccessDecisionManager.php b/src/Symfony/Component/Security/Core/Authorization/DebugAccessDecisionManager.php
index 540d998206..1a04bc1f60 100644
--- a/src/Symfony/Component/Security/Core/Authorization/DebugAccessDecisionManager.php
+++ b/src/Symfony/Component/Security/Core/Authorization/DebugAccessDecisionManager.php
@@ -26,17 +26,19 @@ class DebugAccessDecisionManager implements AccessDecisionManagerInterface
 {
     private $manager;
     private $strategy;
-    private $voters;
+    private $voters = array();
     private $decisionLog = array();
 
-    public function __construct(AccessDecisionManager $manager)
+    public function __construct(AccessDecisionManagerInterface $manager)
     {
         $this->manager = $manager;
 
-        // The strategy is stored in a private property of the decorated service
-        $reflection = new \ReflectionProperty($manager, 'strategy');
-        $reflection->setAccessible(true);
-        $this->strategy = $reflection->getValue($manager);
+        if ($this->manager instanceof AccessDecisionManager) {
+            // The strategy is stored in a private property of the decorated service
+            $reflection = new \ReflectionProperty(AccessDecisionManager::class, 'strategy');
+            $reflection->setAccessible(true);
+            $this->strategy = $reflection->getValue($manager);
+        }
     }
 
     /**
@@ -60,6 +62,10 @@ class DebugAccessDecisionManager implements AccessDecisionManagerInterface
      */
     public function setVoters(array $voters)
     {
+        if (!$this->manager instanceof AccessDecisionManager) {
+            return;
+        }
+
         $this->voters = $voters;
         $this->manager->setVoters($voters);
     }
@@ -72,7 +78,7 @@ class DebugAccessDecisionManager implements AccessDecisionManagerInterface
         // The $strategy property is misleading because it stores the name of its
         // method (e.g. 'decideAffirmative') instead of the original strategy name
         // (e.g. 'affirmative')
-        return strtolower(substr($this->strategy, 6));
+        return null === $this->strategy ? '-' : strtolower(substr($this->strategy, 6));
     }
 
     /**