diff --git a/Service/CircuitBreakerService.php b/Service/CircuitBreakerService.php
index 5858b3f..1ef3fe0 100644
--- a/Service/CircuitBreakerService.php
+++ b/Service/CircuitBreakerService.php
@@ -82,7 +82,7 @@ public function isOpen(string $service): bool
             $this->status[$service] = self::OPEN;
         }
 
-        return $this->status[$service] === self::OPEN;
+        return isset($this->status[$service]) && $this->status[$service] === self::OPEN;
     }
 
     /**