diff --git a/src/priv/countstates.hh b/src/priv/countstates.hh
index 03437bbd0..9c0c23a10 100644
--- a/src/priv/countstates.hh
+++ b/src/priv/countstates.hh
@@ -1,5 +1,5 @@
 // -*- coding: utf-8 -*-
-// Copyright (C) 2013 Laboratoire de Recherche et Développement
+// Copyright (C) 2013, 2014 Laboratoire de Recherche et Développement
 // de l'Epita (LRDE).
 //
 // This file is part of Spot, a model checking library.
@@ -20,10 +20,16 @@
 #ifndef SPOT_PRIV_COUNTSTATES_HH
 # define SPOT_PRIV_COUNTSTATES_HH
 
+#include "misc/common.hh"
+
 namespace spot
 {
   class tgba;
   unsigned count_states(const tgba* a);
+
+  class tgba_digraph;
+  // Call a->num_states() directly!
+  unsigned count_states(const tgba_digraph* a) SPOT_DEPRECATED;
 }
 
 #endif // SPOT_PRIV_COUNTSTATES_HH