diff --git a/clutter/clutter-stage.c b/clutter/clutter-stage.c
index b3d8a6fbb..0a553c26f 100644
--- a/clutter/clutter-stage.c
+++ b/clutter/clutter-stage.c
@@ -2690,10 +2690,16 @@ _clutter_stage_maybe_setup_viewport (ClutterStage *stage)
                          priv->viewport[2],
                          priv->viewport[3]);
 
+
+      priv->dirty_viewport = FALSE;
     }
 
   if (priv->dirty_projection)
-    cogl_set_projection_matrix (&priv->projection);
+    {
+      cogl_set_projection_matrix (&priv->projection);
+
+      priv->dirty_projection = FALSE;
+    }
 }
 
 /**