diff --git a/gtk/gtklistbox.c b/gtk/gtklistbox.c
index 95120f8cef..3a75bc0f3e 100644
--- a/gtk/gtklistbox.c
+++ b/gtk/gtklistbox.c
@@ -1078,7 +1078,7 @@ gtk_list_box_set_adjustment (GtkListBox    *box,
  * Gets the adjustment (if any) that the widget uses to
  * for vertical scrolling.
  *
- * Returns: (transfer none): the adjustment
+ * Returns: (transfer none) (nullable): the adjustment
  */
 GtkAdjustment *
 gtk_list_box_get_adjustment (GtkListBox *box)