diff --git a/phpseclib/Net/SSH2.php b/phpseclib/Net/SSH2.php
index 2da1e0a7..171950c1 100644
--- a/phpseclib/Net/SSH2.php
+++ b/phpseclib/Net/SSH2.php
@@ -3277,7 +3277,7 @@ class SSH2
      */
     function _disconnect($reason)
     {
-        if ($this->bitmap & NET_SSH2_MASK_CONNECTED) {
+        if ($this->bitmap & self::MASK_CONNECTED) {
             $data = pack('CNNa*Na*', NET_SSH2_MSG_DISCONNECT, $reason, 0, '', 0, '');
             $this->_send_binary_packet($data);
             $this->bitmap = 0;