Index: tol/btol/real_type/datgrav.cpp
===================================================================
--- tol/btol/real_type/datgrav.cpp	(revision 3f1b78caea4867daf4948774d6bf76564bc37568)
+++ tol/btol/real_type/datgrav.cpp	(revision 4b82a48fcfa8b032f6c8db7e1850ddb3522461e7)
@@ -813,4 +813,5 @@
       if(oldEnabled) { BOut::Enable(); }
     }
+    if(result && (result->Grammar()!=gra)) { result=NULL; }
   }
   contens_ = result!=NULL;