diff --git a/src/h3.c b/src/h3.c
index e7cbac445..7b6961be6 100644
--- a/src/h3.c
+++ b/src/h3.c
@@ -1847,9 +1847,6 @@ static size_t h3_snd_buf(struct qcs *qcs, struct buffer *buf, size_t count)
 
 	htx = htx_from_buf(buf);
 
-	if (htx->extra && htx->extra == HTX_UNKOWN_PAYLOAD_LENGTH)
-		qcs->flags |= QC_SF_UNKNOWN_PL_LENGTH;
-
 	while (count && !htx_is_empty(htx) && !(qcs->flags & QC_SF_BLK_MROOM)) {
 		idx = htx_get_head(htx);
 		blk = htx_get_blk(htx, idx);
diff --git a/src/hq_interop.c b/src/hq_interop.c
index 14f83b79d..0bbf44c5a 100644
--- a/src/hq_interop.c
+++ b/src/hq_interop.c
@@ -99,9 +99,6 @@ static size_t hq_interop_snd_buf(struct qcs *qcs, struct buffer *buf,
 
 	htx = htx_from_buf(buf);
 
-	if (htx->extra && htx->extra == HTX_UNKOWN_PAYLOAD_LENGTH)
-		qcs->flags |= QC_SF_UNKNOWN_PL_LENGTH;
-
 	while (count && !htx_is_empty(htx) && !(qcs->flags & QC_SF_BLK_MROOM)) {
 		/* Not implemented : QUIC on backend side */
 		idx = htx_get_head(htx);
diff --git a/src/qmux_http.c b/src/qmux_http.c
index edf26b141..3c5f3917c 100644
--- a/src/qmux_http.c
+++ b/src/qmux_http.c
@@ -78,6 +78,15 @@ size_t qcs_http_snd_buf(struct qcs *qcs, struct buffer *buf, size_t count,
 	TRACE_ENTER(QMUX_EV_STRM_SEND, qcs->qcc->conn, qcs);
 
 	htx = htxbuf(buf);
+
+	/* Extra care required for HTTP/1 responses without Content-Length nor
+	 * chunked encoding. In this case, shutw callback will be use to signal
+	 * the end of the message. QC_SF_UNKNOWN_PL_LENGTH is set to prevent a
+	 * RESET_STREAM emission in this case.
+	 */
+	if (htx->extra && htx->extra == HTX_UNKOWN_PAYLOAD_LENGTH)
+		qcs->flags |= QC_SF_UNKNOWN_PL_LENGTH;
+
 	eom = (htx->flags & HTX_FL_EOM);
 	ret = qcs->qcc->app_ops->snd_buf(qcs, buf, count);
 	*fin = (eom && !b_data(buf));