Clarification.
diff --git a/Doc/library/ftplib.rst b/Doc/library/ftplib.rst
index e3e546c..f9b6481 100644
--- a/Doc/library/ftplib.rst
+++ b/Doc/library/ftplib.rst
@@ -231,9 +231,9 @@
    Retrieve a file or directory listing in ASCII transfer mode.  *cmd*
    should be an appropriate ``RETR`` command (see :meth:`retrbinary`) or a
    command such as ``LIST``, ``NLST`` or ``MLSD`` (usually just the string
-   ``'LIST'``).  The *callback* function is called for each line, with the
-   trailing CRLF stripped.  The default *callback* prints the line to
-   ``sys.stdout``.
+   ``'LIST'``).  The *callback* function is called for each line with a
+   string argument containing the line with the trailing CRLF stripped.
+   The default *callback* prints the line to ``sys.stdout``.
 
 
 .. method:: FTP.set_pasv(boolean)