diff --git a/src/core/gcal-calendar.c b/src/core/gcal-calendar.c
index 51752ad2..a8bdbbbd 100644
--- a/src/core/gcal-calendar.c
+++ b/src/core/gcal-calendar.c
@@ -189,11 +189,10 @@ on_source_color_changed_cb (ESourceSelectable *source,
                             GParamSpec        *pspec,
                             GcalCalendar      *self)
 {
-  g_autoptr (GMutexLocker) locker = NULL;
   GcalCalendarPrivate *priv;
 
   priv = gcal_calendar_get_instance_private (self);
-  locker = g_mutex_locker_new (&priv->shared.mutex);
+  G_MUTEX_AUTO_LOCK (&priv->shared.mutex, locker);
 
   priv->shared.color_changed = TRUE;
   schedule_idle_update_unlocked (self);