Index: src/natools-s_expressions-generic_caches.ads
==================================================================
--- src/natools-s_expressions-generic_caches.ads
+++ src/natools-s_expressions-generic_caches.ads
@@ -130,11 +130,11 @@
       Exp : Trees.Reference;
    end record;
 
 
    type Cursor is new Descriptor with record
-      Exp : Trees.Reference := Trees.Create (Create_Tree'Access);
+      Exp : Trees.Reference := Trees.Null_Reference;
       Position : Node_Access := null;
       Opening : Boolean := False;
    end record;
 
 end Natools.S_Expressions.Generic_Caches;