diff --git a/src/plugins/irc/irc-server.c b/src/plugins/irc/irc-server.c
index c058ba9d1..3b42d1d12 100644
--- a/src/plugins/irc/irc-server.c
+++ b/src/plugins/irc/irc-server.c
@@ -3528,7 +3528,11 @@ irc_server_create_buffer (struct t_irc_server *server)
 /*
  * GnuTLS callback called during handshake.
  *
+ * Returns:
+ *    0: certificate OK
+ *   -1: error in certificate
  */
+
 int
 irc_server_gnutls_callback (void *data, gnutls_session_t tls_session,
                             const gnutls_datum_t *req_ca, int nreq,