diff --git a/gtk/gtkcssnode.c b/gtk/gtkcssnode.c
index ab52c2bcd3..ebc65a8d43 100644
--- a/gtk/gtkcssnode.c
+++ b/gtk/gtkcssnode.c
@@ -1353,6 +1353,8 @@ gtk_css_node_validate (GtkCssNode *cssnode)
   gint64 timestamp;
   gint64 before = g_get_monotonic_time ();
 
+  g_assert (cssnode->parent == NULL);
+
   timestamp = gtk_css_node_get_timestamp (cssnode);
 
   gtk_css_node_validate_internal (cssnode, &filter, timestamp);
diff --git a/gtk/gtkpopover.c b/gtk/gtkpopover.c
index 168a51a892..752c8b9777 100644
--- a/gtk/gtkpopover.c
+++ b/gtk/gtkpopover.c
@@ -647,7 +647,6 @@ gtk_popover_show (GtkWidget *widget)
   GtkPopoverPrivate *priv = gtk_popover_get_instance_private (popover);
 
   _gtk_widget_set_visible_flag (widget, TRUE);
-  gtk_css_node_validate (gtk_widget_get_css_node (widget));
   gtk_widget_realize (widget);
   gtk_popover_native_check_resize (GTK_NATIVE (widget));
   gtk_widget_map (widget);