diff --git a/src/mux_quic.c b/src/mux_quic.c
index cce191bd7..c2364bfac 100644
--- a/src/mux_quic.c
+++ b/src/mux_quic.c
@@ -1473,6 +1473,7 @@ static int qcs_build_stream_frm(struct qcs *qcs, struct buffer *out, char fin,
 	frm->stream.buf = out;
 	frm->stream.data = (unsigned char *)b_peek(out, head);
 	frm->stream.offset.key = 0;
+	frm->stream.dup = 0;
 
 	/* FIN is positioned only when the buffer has been totally emptied. */
 	if (fin)