diff --git a/phpseclib/Net/SFTP.php b/phpseclib/Net/SFTP.php
index 110cd1c7..c0f24fc8 100644
--- a/phpseclib/Net/SFTP.php
+++ b/phpseclib/Net/SFTP.php
@@ -1042,7 +1042,7 @@ class Net_SFTP extends Net_SSH2
      */
     function truncate($filename, $new_size)
     {
-        $attr = pack('N3', NET_SFTP_ATTR_SIZE, $new_size / 4294967296, $new_size);
+        $attr = pack('N3', NET_SFTP_ATTR_SIZE, $new_size / 4294967296, $new_size); // 4294967296 == 0x100000000 == 1<<32
 
         return $this->_setstat($filename, $attr, false);
     }