retval := make([]corev1.Namespace, 0, len(namespaces))
	seen := sets.String{}
	for _, webhook := range hook.Webhooks {
		nsSelector, err := metav1.LabelSelectorAsSelector(webhook.NamespaceSelector)
		if err != nil {
			return retval
		}

		for _, namespace := range namespaces {
			if !seen.Contains(namespace.Name) && nsSelector.Matches(api_pkg_labels.Set(namespace.Labels)) {