diff --git a/pl/flags.yap b/pl/flags.yap
index 13ccbb4bc..48a312bb3 100644
--- a/pl/flags.yap
+++ b/pl/flags.yap
@@ -741,23 +741,21 @@ yap_flag(stack_dump_on_error,X) :-
 
 yap_flag(user_input,OUT) :-
 	var(OUT), !,
-	'$flag_check_alias'(OUT, user_input).
-	
+	stream_property(OUT,alias(user_input)).
 yap_flag(user_input,Stream) :-
-	'$change_alias_to_stream'(user_input,Stream).
+	set_stream(Stream, alias(user_input).
 
 yap_flag(user_output,OUT) :-
 	var(OUT), !,
-	'$flag_check_alias'(OUT, user_output).
+	stream_property(OUT,alias(user_output)).
 yap_flag(user_output,Stream) :-
-	'$change_alias_to_stream'(user_output,Stream).
-
+	set_stream(Stream, alias(user_output).
 
 yap_flag(user_error,OUT) :-
 	var(OUT), !,
-	'$flag_check_alias'(OUT, user_error).
+	stream_property(OUT,alias(user_error)).
 yap_flag(user_error,Stream) :-
-	'$change_alias_to_stream'(user_error,Stream).
+	set_stream(Stream, alias(user_error).
 
 yap_flag(debugger_print_options,OUT) :-
 	var(OUT),