diff --git a/lib/Auth/Process/SwitchAuth.php b/lib/Auth/Process/SwitchAuth.php
index 044d92186ef8a6cb8c6ae72bb2861091ce95e8c5..043ab2889f60a86edb493345915fbb66976f80c6 100644
--- a/lib/Auth/Process/SwitchAuth.php
+++ b/lib/Auth/Process/SwitchAuth.php
@@ -254,10 +254,10 @@ class SwitchAuth extends \SimpleSAML\Auth\ProcessingFilter
             return false;
         }
 
-        if ($attributes[$this->sfa_alphabet_attr] >= 52 && $attributes[$this->sfa_len_attr] >= 12) {
+        if ($attributes[$this->sfa_alphabet_attr][0] >= 52 && $attributes[$this->sfa_len_attr][0] >= 12) {
             return true;
         }
-        if ($attributes[$this->sfa_alphabet_attr] >= 72 && $attributes[$this->sfa_len_attr] >= 8) {
+        if ($attributes[$this->sfa_alphabet_attr][0] >= 72 && $attributes[$this->sfa_len_attr][0] >= 8) {
             return true;
         }