diff --git a/glib/giochannel.c b/glib/giochannel.c
index 4cf205a70..2b5d7a740 100644
--- a/glib/giochannel.c
+++ b/glib/giochannel.c
@@ -878,10 +878,10 @@ g_io_channel_get_buffer_size (GIOChannel *channel)
 /**
  * g_io_channel_set_line_term:
  * @channel: a #GIOChannel
- * @line_term: The line termination string. Use %NULL for autodetect.
- *             Autodetection breaks on "\n", "\r\n", "\r", "\0", and
- *             the Unicode paragraph separator. Autodetection should
- *             not be used for anything other than file-based channels.
+ * @line_term: (allow-none): The line termination string. Use %NULL for
+ *             autodetect.  Autodetection breaks on "\n", "\r\n", "\r", "\0",
+ *             and the Unicode paragraph separator. Autodetection should not be
+ *             used for anything other than file-based channels.
  * @length: The length of the termination string. If -1 is passed, the
  *          string is assumed to be nul-terminated. This option allows
  *          termination strings with embedded nuls.
@@ -1282,7 +1282,7 @@ g_io_channel_get_buffered (GIOChannel *channel)
 /**
  * g_io_channel_set_encoding:
  * @channel: a #GIOChannel
- * @encoding: the encoding type
+ * @encoding: (allow-none): the encoding type
  * @error: location to store an error of type #GConvertError
  *
  * Sets the encoding for the input/output of the channel.