diff --git a/src/mux_h2.c b/src/mux_h2.c
index 6ff52d0d8..a870426dc 100644
--- a/src/mux_h2.c
+++ b/src/mux_h2.c
@@ -8097,6 +8097,15 @@ static size_t h2_nego_ff(struct stconn *sc, struct buffer *input, size_t count,
 
 	TRACE_ENTER(H2_EV_H2S_SEND|H2_EV_STRM_SEND, h2s->h2c->conn, h2s);
 
+	if (h2s->st >= H2_SS_HLOC) {
+		/* Cannot emit any new data if stream already closed. Data
+		 * draining will be performed via snd_buf.
+		 */
+		TRACE_DEVEL("stream already closed, disable FF", H2_EV_H2S_SEND, h2s->h2c->conn, h2s);
+		h2s->sd->iobuf.flags |= IOBUF_FL_NO_FF;
+		goto end;
+	}
+
 	/* If we were not just woken because we wanted to send but couldn't,
 	 * and there's somebody else that is waiting to send, do nothing,
 	 * we will subscribe later and be put at the end of the list
diff --git a/src/mux_quic.c b/src/mux_quic.c
index b24f2086b..14afb4073 100644
--- a/src/mux_quic.c
+++ b/src/mux_quic.c
@@ -4167,6 +4167,15 @@ static size_t qmux_strm_nego_ff(struct stconn *sc, struct buffer *input,
 		goto end;
 	}
 
+	if (qcs_is_close_local(qcs) || (qcs->flags & QC_SF_TO_RESET)) {
+		/* Cannot emit any new data if stream already closed. Data
+		 * draining will be performed via snd_buf.
+		 */
+		TRACE_DEVEL("stream already closed", QMUX_EV_STRM_SEND, qcs->qcc->conn, qcs);
+		qcs->sd->iobuf.flags |= IOBUF_FL_NO_FF;
+		goto end;
+	}
+
 	if (LIST_INLIST(&qcs->el_buf)) {
 		TRACE_DEVEL("leaving on no buf avail", QMUX_EV_STRM_SEND, qcs->qcc->conn, qcs);
 		qcs->sd->iobuf.flags |= IOBUF_FL_FF_BLOCKED;