diff --git a/gtk/gtkbin.c b/gtk/gtkbin.c
index 7323d075fa..90f2ddea17 100644
--- a/gtk/gtkbin.c
+++ b/gtk/gtkbin.c
@@ -199,7 +199,8 @@ gtk_bin_measure (GtkWidget *widget,
  * no child widget. The returned widget does not have a reference
  * added, so you do not need to unref it.
  *
- * Returns: (transfer none): pointer to child of the #GtkBin
+ * Returns: (transfer none) (nullable): the child of @bin, or %NULL if it does
+ * not have a child.
  **/
 GtkWidget*
 gtk_bin_get_child (GtkBin *bin)
diff --git a/gtk/gtkwidget.c b/gtk/gtkwidget.c
index 5edc2a2a3c..3f72a7edc4 100644
--- a/gtk/gtkwidget.c
+++ b/gtk/gtkwidget.c
@@ -9181,9 +9181,10 @@ gtk_widget_set_parent_window (GtkWidget *widget,
  * gtk_widget_get_parent_window:
  * @widget: a #GtkWidget.
  *
- * Gets @widget’s parent window.
+ * Gets @widget’s parent window, or %NULL if it does not have one.
  *
- * Returns: (transfer none): the parent window of @widget.
+ * Returns: (transfer none) (nullable): the parent window of @widget, or %NULL
+ * if it does not have a parent window.
  **/
 GdkWindow *
 gtk_widget_get_parent_window (GtkWidget *widget)