diff --git a/src/Symfony/Component/Security/Core/Authorization/AccessDecisionManager.php b/src/Symfony/Component/Security/Core/Authorization/AccessDecisionManager.php
index 39cca72b7b9bc..5f5104f2a5b99 100644
--- a/src/Symfony/Component/Security/Core/Authorization/AccessDecisionManager.php
+++ b/src/Symfony/Component/Security/Core/Authorization/AccessDecisionManager.php
@@ -42,8 +42,9 @@ class AccessDecisionManager implements AccessDecisionManagerInterface
      */
     public function __construct($voters = [], $strategy = self::STRATEGY_AFFIRMATIVE, $allowIfAllAbstainDecisions = false, $allowIfEqualGrantedDeniedDecisions = true)
     {
+        $strategy = (string) $strategy;
         $strategyMethod = 'decide'.ucfirst($strategy);
-        if (!\is_callable([$this, $strategyMethod])) {
+        if (!\is_callable([$this, $strategyMethod]) || 0 === \strlen($strategy)) {
             throw new \InvalidArgumentException(sprintf('The strategy "%s" is not supported.', $strategy));
         }