diff --git a/src/lib/builtins.pl b/src/lib/builtins.pl
index ff08ca9d..910d0269 100644
--- a/src/lib/builtins.pl
+++ b/src/lib/builtins.pl
@@ -126,9 +126,9 @@ Module : Predicate :-
 
 % flags.
 
-current_prolog_flag(Flag, false) :- Flag == bounded, !.
+current_prolog_flag(Flag, Value) :- Flag == bounded, !, Value == false.
 current_prolog_flag(bounded, false).
-current_prolog_flag(Flag, toward_zero) :- Flag == integer_rounding_function, !.
+current_prolog_flag(Flag, Value) :- Flag == integer_rounding_function, !, Value == toward_zero.
 current_prolog_flag(integer_rounding_function, toward_zero).
 current_prolog_flag(Flag, Value) :- Flag == double_quotes, !, '$get_double_quotes'(Value).
 current_prolog_flag(double_quotes, Value) :- '$get_double_quotes'(Value).