diff --git a/Validator/CaptchaValidator.php b/Validator/CaptchaValidator.php
index 4469cec..2c4485f 100644
--- a/Validator/CaptchaValidator.php
+++ b/Validator/CaptchaValidator.php
@@ -60,7 +60,7 @@ class CaptchaValidator
         $this->session          = $session;
         $this->key              = $key;
         $this->invalidMessage   = $invalidMessage;
-        $this->bypassCode       = $bypassCode;
+        $this->bypassCode       = (string)$bypassCode;
         $this->humanity         = $humanity;
     }