diff --git a/lib/SimpleSAML/XML/Signer.php b/lib/SimpleSAML/XML/Signer.php
index 5ab89acd661a71d4d72f420b0731e875a7718148..f84a335448fa88d654228595e444827841d55b68 100644
--- a/lib/SimpleSAML/XML/Signer.php
+++ b/lib/SimpleSAML/XML/Signer.php
@@ -39,7 +39,7 @@ class Signer
 
 
     /**
-     * @var string Extra certificates which should be included in the response.
+     * @var array Extra certificates which should be included in the response.
      */
     private $extraCertificates;