diff --git a/prolog/metta_lang/metta_eval.pl b/prolog/metta_lang/metta_eval.pl
index 7901b9c15a..7fe1192d73 100755
--- a/prolog/metta_lang/metta_eval.pl
+++ b/prolog/metta_lang/metta_eval.pl
@@ -682,7 +682,7 @@
   maplist(println_impl,Out),
   make_nop(RetType,[],Res),check_returnval(Eq,RetType,Res).
 
-println_impl(X):- format("~N~@~N",[write_sln(X)]),!,flush_output.
+println_impl(X):- ttyflush,user_io((format("~N~@~N",[write_sln(X)]))),!,flush_output,ttyflush.
 %println_impl(X):- user_io((ansi_format(fg('#c7ea46'),"~N~@~N",[write_sln(X)]))),flush_output.
 %println_impl(X):- ((ansi_format(fg('#c7ea46'),"~N~@~N",[write_sln(X)]))),flush_output.