diff --git a/phpseclib/Net/SFTP.php b/phpseclib/Net/SFTP.php
index 577027eb..dbc14ede 100644
--- a/phpseclib/Net/SFTP.php
+++ b/phpseclib/Net/SFTP.php
@@ -1083,7 +1083,7 @@ class Net_SFTP extends Net_SSH2
             uasort($contents, array(&$this, '_comparator'));
         }
 
-        return $raw ? $contents : array_keys($contents);
+        return $raw ? $contents : array_map('strval', array_keys($contents));
     }
 
     /**