diff --git a/phpseclib/File/X509.php b/phpseclib/File/X509.php
index 649e007d..af66b217 100644
--- a/phpseclib/File/X509.php
+++ b/phpseclib/File/X509.php
@@ -3467,7 +3467,7 @@ class X509
         $altName = array();
 
         if (isset($subject->domains) && count($subject->domains) > 1) {
-            $altName = array_map(array('X509', '_dnsName'), $subject->domains);
+            $altName = array_map(array('\phpseclib\File\X509', '_dnsName'), $subject->domains);
         }
 
         if (isset($subject->ipAddresses) && count($subject->ipAddresses)) {