diff --git a/pl/corout.yap b/pl/corout.yap
index 21509fcea..d5d8b0521 100644
--- a/pl/corout.yap
+++ b/pl/corout.yap
@@ -37,17 +37,27 @@
 	   '$show_frozen_goals'(Level))).
 
 '$project_and_delayed_goals'(G,LGs) :-
-	attributes:all_attvars(LAV),
+	'$att_vars'(G, LAV),
 	LAV = [_|_], !,
 	% SICStus compatible step,
 	% just try to simplify store  by projecting constraints
 	% over query variables.
 	'$project_attributes'(LAV, G),
 	% now get a list of frozen goals.
-	attributes:all_attvars(NLAV),
+	'$att_vars'(G, NLAV),
 	'$get_goalist_from_attvars'(NLAV, LGs).
 '$project_and_delayed_goals'(_,[]).
 
+'$att_vars'(Term, LAV) :-
+	term_variables(Term, TVars),
+	'$select_atts'(TVars, LAV).
+
+'$select_atts'([], []).
+'$select_atts'(V.TVars, V.LAV) :-
+	attvar(V), !,
+	'$select_atts'(TVars, LAV).
+'$select_atts'(V.TVars, LAV) :-
+	'$select_atts'(TVars, LAV).
 
 %
 % wake_up_goal is called by the system whenever a suspended goal
@@ -553,7 +563,8 @@ frozen(V, LG) :-
 	'$fetch_same_done_goals'(G0, D0, LV, GF).
 
 
-call_residue_vars(Goal,Residue) :-
+/*
+call_residue_vars(Goal,Vars) :-
 	attributes:all_attvars(Vs0),
 	call(Goal),
 	attributes:all_attvars(Vs),
@@ -575,50 +586,13 @@ call_residue_vars(Goal,Residue) :-
 	;
 	  '$ord_remove'([V1|Vss], Vs0s, Residue)
 	).
+*/
 
 copy_term(Term, Copy, Goals) :-
 	term_variables(Term, TVars),
 	'$get_goalist_from_attvars'(TVars, Goals0),
 	copy_term_nat([Term|Goals0], [Copy|Goals]).
 
-call_residue(Goal,Residue) :-
-	var(Goal), !,
-	'$do_error'(instantiation_error,call_residue(Goal,Residue)).
-call_residue(Module:Goal,Residue) :-
-	atom(Module), !,
-	'$call_residue'(Goal,Module,Residue).
-call_residue(Goal,Residue) :-
-	'$current_module'(Module),
-	'$call_residue'(Goal,Module,Residue).
-
-'$call_residue'(Goal,Module,Residue) :-
-	'$read_svar_list'(OldAttsList),
-	copy_term_nat(Goal, NGoal),
-	( '$set_svar_list'(CurrentAttsList),
-	  '$system_catch'(NGoal,Module,Error,'$residue_catch_trap'(Error,OldAttsList)),
-	  '$project_and_delayed_goals'(NGoal,Residue0),
-	  '$add_vs_to_vlist'(Residue0, Residue),
-	  ( '$set_svar_list'(OldAttsList),
-	    copy_term_nat(NGoal+NResidue, Goal+Residue)
-	  ;
-	    '$set_svar_list'(CurrentAttsList), fail
-	  )
-	;
-          '$set_svar_list'(OldAttsList), fail
-        ).
-
-'$add_vs_to_vlist'([], []).
-'$add_vs_to_vlist'([G|Residue0], [Vs-G|Residue]) :-
-	term_variables(G, TVs),
-	'$pick_att_vars'(TVs, Vs),
-	'$add_vs_to_vlist'(Residue0, Residue).
-
-
-% make sure we set the suspended goal list to its previous state!
-'$residue_catch_trap'(Error,OldAttsList) :-
-	'$set_svar_list'(OldAttsList),
-	throw(Error).
-
 % make sure we have installed a SICStus like constraint solver.
 '$project_attributes'(_, _) :-
 	'$undefined'(modules_with_attributes(_),attributes), !.