diff --git a/include/haproxy/mux_quic.h b/include/haproxy/mux_quic.h
index ca5cd56e7..b91ccdcbd 100644
--- a/include/haproxy/mux_quic.h
+++ b/include/haproxy/mux_quic.h
@@ -23,6 +23,7 @@ void qcs_notify_recv(struct qcs *qcs);
 void qcs_notify_send(struct qcs *qcs);
 
 struct buffer *qcc_get_stream_rxbuf(struct qcs *qcs);
+struct buffer *qcc_get_stream_txbuf(struct qcs *qcs);
 void qcc_reset_stream(struct qcs *qcs, int err);
 void qcc_send_stream(struct qcs *qcs, int urg);
 void qcc_abort_stream_read(struct qcs *qcs);
diff --git a/src/h3.c b/src/h3.c
index d7bf11010..ba488f26f 100644
--- a/src/h3.c
+++ b/src/h3.c
@@ -1415,17 +1415,6 @@ static ssize_t h3_decode_qcs(struct qcs *qcs, struct buffer *b, int fin)
 	return -1;
 }
 
-/* Returns buffer for data sending.
- * May be NULL if the allocation failed.
- */
-static struct buffer *mux_get_buf(struct qcs *qcs)
-{
-	if (!b_size(&qcs->tx.buf))
-		b_alloc(&qcs->tx.buf);
-
-	return &qcs->tx.buf;
-}
-
 /* Function used to emit stream data from <qcs> control uni-stream */
 static int h3_control_send(struct qcs *qcs, void *ctx)
 {
@@ -1464,7 +1453,7 @@ static int h3_control_send(struct qcs *qcs, void *ctx)
 		b_quic_enc_int(&pos, h3_settings_max_field_section_size, 0);
 	}
 
-	res = mux_get_buf(qcs);
+	res = qcc_get_stream_txbuf(qcs);
 	if (b_room(res) < b_data(&pos)) {
 		// TODO the mux should be put in blocked state, with
 		// the stream in state waiting for settings to be sent
@@ -1533,7 +1522,8 @@ static int h3_resp_headers_send(struct qcs *qcs, struct htx *htx)
 
 	list[hdr].n = ist("");
 
-	res = mux_get_buf(qcs);
+	if (!(res = qcc_get_stream_txbuf(qcs)))
+		goto err;
 
 	/* At least 5 bytes to store frame type + length as a varint max size */
 	if (b_room(res) < 5)
@@ -1663,7 +1653,8 @@ static int h3_resp_trailers_send(struct qcs *qcs, struct htx *htx)
 	}
 	list[hdr].n = ist("");
 
-	res = mux_get_buf(qcs);
+	if (!(res = qcc_get_stream_txbuf(qcs)))
+		goto err;
 
 	/* At least 9 bytes to store frame type + length as a varint max size */
 	if (b_room(res) < 9) {
@@ -1769,7 +1760,9 @@ static int h3_resp_data_send(struct qcs *qcs, struct buffer *buf, size_t count)
 	if (type != HTX_BLK_DATA)
 		goto end;
 
-	res = mux_get_buf(qcs);
+	if (!(res = qcc_get_stream_txbuf(qcs))) {
+		/* TODO */
+	}
 
 	if (unlikely(fsize == count &&
 		     !b_data(res) &&
@@ -1947,8 +1940,9 @@ static size_t h3_nego_ff(struct qcs *qcs, size_t count)
 
 	h3_debug_printf(stderr, "%s\n", __func__);
 
-	/* FIXME: no check on ALLOC ? */
-	res = mux_get_buf(qcs);
+	if (!(res = qcc_get_stream_txbuf(qcs))) {
+		/* TODO */
+	}
 
 	/* h3 DATA headers : 1-byte frame type + varint frame length */
 	hsize = 1 + QUIC_VARINT_MAX_SIZE;
@@ -2154,7 +2148,7 @@ static int h3_send_goaway(struct h3c *h3c)
 	b_quic_enc_int(&pos, frm_len, 0);
 	b_quic_enc_int(&pos, h3c->id_goaway, 0);
 
-	res = mux_get_buf(qcs);
+	res = qcc_get_stream_txbuf(qcs);
 	if (!res || b_room(res) < b_data(&pos)) {
 		/* Do not try forcefully to emit GOAWAY if no space left. */
 		TRACE_ERROR("cannot send GOAWAY", H3_EV_H3C_END, h3c->qcc->conn, qcs);
diff --git a/src/hq_interop.c b/src/hq_interop.c
index ae4140a88..ba2f0c7db 100644
--- a/src/hq_interop.c
+++ b/src/hq_interop.c
@@ -83,14 +83,6 @@ static ssize_t hq_interop_decode_qcs(struct qcs *qcs, struct buffer *b, int fin)
 	return b_data(b);
 }
 
-static struct buffer *mux_get_buf(struct qcs *qcs)
-{
-	if (!b_size(&qcs->tx.buf))
-		b_alloc(&qcs->tx.buf);
-
-	return &qcs->tx.buf;
-}
-
 static size_t hq_interop_snd_buf(struct qcs *qcs, struct buffer *buf,
                                  size_t count)
 {
@@ -102,7 +94,7 @@ static size_t hq_interop_snd_buf(struct qcs *qcs, struct buffer *buf,
 	struct buffer *res, outbuf;
 	size_t total = 0;
 
-	res = mux_get_buf(qcs);
+	res = qcc_get_stream_txbuf(qcs);
 	outbuf = b_make(b_tail(res), b_contig_space(res), 0, 0);
 
 	htx = htx_from_buf(buf);
@@ -163,7 +155,7 @@ static size_t hq_interop_snd_buf(struct qcs *qcs, struct buffer *buf,
 
 static size_t hq_interop_nego_ff(struct qcs *qcs, size_t count)
 {
-	struct buffer *res = mux_get_buf(qcs);
+	struct buffer *res = qcc_get_stream_txbuf(qcs);
 
 	if (!b_room(res)) {
 		qcs->flags |= QC_SF_BLK_MROOM;
diff --git a/src/mux_quic.c b/src/mux_quic.c
index 4fbef0d9d..4422e0ba1 100644
--- a/src/mux_quic.c
+++ b/src/mux_quic.c
@@ -914,6 +914,15 @@ struct buffer *qcc_get_stream_rxbuf(struct qcs *qcs)
 	return b_alloc(&qcs->rx.app_buf);
 }
 
+/* Allocate if needed and retrieve <qcs> stream buffer for data emission.
+ *
+ * Returns buffer pointer. May be NULL on allocation failure.
+ */
+struct buffer *qcc_get_stream_txbuf(struct qcs *qcs)
+{
+	return b_alloc(&qcs->tx.buf);
+}
+
 /* Prepare for the emission of RESET_STREAM on <qcs> with error code <err>. */
 void qcc_reset_stream(struct qcs *qcs, int err)
 {