···11+diff --git a/src/elpi_trace_elaborator.ml b/src/elpi_trace_elaborator.ml
22+index ca13114d..093e7593 100644
33+--- a/src/elpi_trace_elaborator.ml
44++++ b/src/elpi_trace_elaborator.ml
55+@@ -664,6 +664,6 @@ let main =
66+77+ let cards = Trace.cards steps ~stack_frames ~aggregated_goal_success ~goal_text ~goal_attempts in
88+99+- let ob = Bi_outbuf.create_channel_writer stdout in
1010++ let ob = Buffer.create 17 in
1111+ write_trace ob cards;
1212+- Bi_outbuf.flush_channel_writer ob
1313++ Buffer.output_buffer stdout ob