diff --git a/ChangeLog b/ChangeLog
index b93351c7..6cd3ebe5 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+2005-08-09  Havoc Pennington  <hp@redhat.com>
+
+	* dbus/dbus-message.c (dbus_message_set_reply_serial): print
+	warning if the reply serial is set to 0
+
 2005-08-04  Colin Walters  <walters@verbum.org>
 
 	* glib/dbus-gvalue-utils.h (_dbus_g_type_specialized_builtins_init)
diff --git a/dbus/dbus-message.c b/dbus/dbus-message.c
index 0b5bc63e..eb0e86cc 100644
--- a/dbus/dbus-message.c
+++ b/dbus/dbus-message.c
@@ -402,6 +402,7 @@ dbus_message_set_reply_serial (DBusMessage   *message,
 {
   _dbus_return_val_if_fail (message != NULL, FALSE);
   _dbus_return_val_if_fail (!message->locked, FALSE);
+  _dbus_return_val_if_fail (reply_serial != 0, FALSE); /* 0 is invalid */
 
   return _dbus_header_set_field_basic (&message->header,
                                        DBUS_HEADER_FIELD_REPLY_SERIAL,