Index: gtk/gtkfilechooserdefault.c
===================================================================
--- gtk/gtkfilechooserdefault.c	(revision 21491)
+++ gtk/gtkfilechooserdefault.c	(working copy)
@@ -456,6 +456,7 @@
                                               GtkTreeIter           *child_iter,
                                               GtkTreeIter           *iter);
 static void     set_file_system_backend      (GtkFileChooserDefault *impl);
+static void     unset_file_system_backend    (GtkFileChooserDefault *impl);
 
 
 
@@ -923,6 +924,8 @@
   GtkFileChooserDefault *impl = GTK_FILE_CHOOSER_DEFAULT (object);
   GSList *l;
 
+  unset_file_system_backend (impl);
+
   if (impl->shortcuts_pane_filter_model)
     g_object_unref (impl->shortcuts_pane_filter_model);
 
@@ -5373,6 +5376,19 @@
   profile_end ("end", NULL);
 }
 
+static void
+unset_file_system_backend (GtkFileChooserDefault *impl)
+{
+  g_signal_disconnect_by_func (impl->file_system, "volumes-changed",
+		               G_CALLBACK (volumes_bookmarks_changed_cb), impl);
+  g_signal_disconnect_by_func (impl->file_system, "bookmarks-changed",
+		               G_CALLBACK (volumes_bookmarks_changed_cb), impl);
+
+  g_object_unref (impl->file_system);
+
+  impl->file_system = NULL;
+}
+
 /* This function is basically a do_all function.
  *
  * It sets the visibility on all the widgets based on the current state, and