diff -Nur gnome-screensaver-3.6.0/src/gs-listener-dbus.c gnome-screensaver-3.6.0.new/src/gs-listener-dbus.c
--- gnome-screensaver-3.6.0/src/gs-listener-dbus.c	2012-10-18 16:05:54.393188619 +0200
+++ gnome-screensaver-3.6.0.new/src/gs-listener-dbus.c	2012-10-18 16:05:52.729188556 +0200
@@ -726,7 +726,7 @@
         }
         if (dbus_message_is_method_call (message, GS_SERVICE, "SimulateUserActivity")) {
                 g_signal_emit (listener, signals [SIMULATE_USER_ACTIVITY], 0);
-                return DBUS_HANDLER_RESULT_HANDLED;
+                return send_success_reply (connection, message);
         }
         if (dbus_message_is_method_call (message, "org.freedesktop.DBus.Introspectable", "Introspect")) {
                 return do_introspect (connection, message, local_interface);