diff --git a/src/tgba/tgbaexplicit.hh b/src/tgba/tgbaexplicit.hh
index 46b2c8197..633c12610 100644
--- a/src/tgba/tgbaexplicit.hh
+++ b/src/tgba/tgbaexplicit.hh
@@ -375,7 +375,8 @@ namespace spot
     {
       typedef typename transitions_t::iterator trans_t;
       typedef std::map<int, trans_t> acc_map;
-      typedef Sgi::hash_map<const spot::state*, acc_map> dest_map;
+      typedef Sgi::hash_map<const spot::state*, acc_map,
+			    ptr_hash<spot::state> > dest_map;
 
       typename ls_map::iterator i;
       for (i = ls_.begin(); i != ls_.end(); ++i)