diff --git a/gtk/gtkassistant.c b/gtk/gtkassistant.c
index 891b821e6b..464e6f1b68 100644
--- a/gtk/gtkassistant.c
+++ b/gtk/gtkassistant.c
@@ -1478,6 +1478,7 @@ gtk_assistant_set_current_page (GtkAssistant *assistant,
   GtkAssistantPage *page;
 
   g_return_if_fail (GTK_IS_ASSISTANT (assistant));
+  g_return_if_fail (assistant->pages != NULL);
 
   if (page_num >= 0)
     page = (GtkAssistantPage *) g_list_nth_data (assistant->pages, page_num);