Index: gtk/gtklabel.c
===================================================================
--- gtk/gtklabel.c	(revision 22174)
+++ gtk/gtklabel.c	(working copy)
@@ -1760,11 +1760,10 @@ gtk_label_set_label (GtkLabel    *label,
 		     const gchar *str)
 {
   g_return_if_fail (GTK_IS_LABEL (label));
-  g_return_if_fail (str != NULL);
 
   g_object_freeze_notify (G_OBJECT (label));
 
-  gtk_label_set_label_internal (label, g_strdup (str));
+  gtk_label_set_label_internal (label, g_strdup (str ? str : ""));
   gtk_label_recalculate (label);
 
   g_object_thaw_notify (G_OBJECT (label));
