diff --git a/gtk/gtkcombobox.c b/gtk/gtkcombobox.c
index 2cb2daff04..f4459f46ab 100644
--- a/gtk/gtkcombobox.c
+++ b/gtk/gtkcombobox.c
@@ -5001,10 +5001,12 @@ gtk_combo_box_get_active_iter (GtkComboBox     *combo_box,
 /**
  * gtk_combo_box_set_active_iter:
  * @combo_box: A #GtkComboBox
- * @iter: The #GtkTreeIter
+ * @iter: The #GtkTreeIter, or %NULL
  * 
- * Sets the current active item to be the one referenced by @iter. 
- * @iter must correspond to a path of depth one.
+ * Sets the current active item to be the one referenced by @iter, or
+ * unsets the active item if @iter is %NULL.
+ *
+ * @iter must correspond to a path of depth one, or be %NULL.
  * 
  * Since: 2.4
  */
@@ -5012,11 +5014,13 @@ void
 gtk_combo_box_set_active_iter (GtkComboBox     *combo_box,
                                GtkTreeIter     *iter)
 {
-  GtkTreePath *path;
+  GtkTreePath *path = NULL;
 
   g_return_if_fail (GTK_IS_COMBO_BOX (combo_box));
 
-  path = gtk_tree_model_get_path (gtk_combo_box_get_model (combo_box), iter);
+  if (iter)
+    path = gtk_tree_model_get_path (gtk_combo_box_get_model (combo_box), iter);
+
   gtk_combo_box_set_active_internal (combo_box, path);
   gtk_tree_path_free (path);
 }