diff --git a/libgimpwidgets/gimpruler.c b/libgimpwidgets/gimpruler.c
index 28b428a57b..6b554c3d33 100644
--- a/libgimpwidgets/gimpruler.c
+++ b/libgimpwidgets/gimpruler.c
@@ -921,6 +921,8 @@ gimp_ruler_style_set (GtkWidget *widget,
                         "font-scale", &priv->font_scale,
                         NULL);
 
+  priv->backing_store_valid = FALSE;
+
   if (priv->layout)
     {
       g_object_unref (priv->layout);