diff --git a/PHPGangsta/GoogleAuthenticator.php b/PHPGangsta/GoogleAuthenticator.php
index bf7d116..2af56e7 100644
--- a/PHPGangsta/GoogleAuthenticator.php
+++ b/PHPGangsta/GoogleAuthenticator.php
@@ -151,6 +151,10 @@ public function verifyCode($secret, $code, $discrepancy = 1, $currentTimeSlice =
      */
     public function setCodeLength($length)
     {
+        if ($length < 6) {
+            throw new Exception('Invalid code length, should be >= 6');
+        }
+
         $this->_codeLength = $length;
 
         return $this;