diff --git a/src/mux_h1.c b/src/mux_h1.c
index b09b1b9..3c3bead 100644
--- a/src/mux_h1.c
+++ b/src/mux_h1.c
@@ -1576,7 +1576,7 @@
 		vlen = sz;
 		if (vlen > count) {
 			if (type != HTX_BLK_DATA)
-				goto copy;
+				goto full;
 			vlen = count;
 		}
 
@@ -1592,7 +1592,7 @@
 				h1s->meth = sl->info.req.meth;
 				h1_parse_req_vsn(h1m, sl);
 				if (!htx_reqline_to_h1(sl, &tmp))
-					goto copy;
+					goto full;
 				h1m->flags |= H1_MF_XFER_LEN;
 				if (sl->flags & HTX_SL_F_BODYLESS)
 					h1m->flags |= H1_MF_CLEN;
@@ -1607,7 +1607,7 @@
 				h1s->status = sl->info.res.status;
 				h1_parse_res_vsn(h1m, sl);
 				if (!htx_stline_to_h1(sl, &tmp))
-					goto copy;
+					goto full;
 				if (sl->flags & HTX_SL_F_XFER_LEN)
 					h1m->flags |= H1_MF_XFER_LEN;
 				if (sl->info.res.status < 200 &&
@@ -1654,7 +1654,7 @@
 				if (h1c->px->options2 & (PR_O2_H1_ADJ_BUGCLI|PR_O2_H1_ADJ_BUGSRV))
 					h1_adjust_case_outgoing_hdr(h1s, h1m, &n);
 				if (!htx_hdr_to_h1(n, v, &tmp))
-					goto copy;
+					goto full;
 			  skip_hdr:
 				h1m->state = H1_MSG_HDR_L2_LWS;
 				break;
@@ -1676,7 +1676,7 @@
 						if (h1c->px->options2 & (PR_O2_H1_ADJ_BUGCLI|PR_O2_H1_ADJ_BUGSRV))
 							h1_adjust_case_outgoing_hdr(h1s, h1m, &n);
 						if (!htx_hdr_to_h1(n, v, &tmp))
-							goto copy;
+							goto full;
 					}
 					h1s->flags |= H1S_F_HAVE_O_CONN;
 				}
@@ -1694,7 +1694,7 @@
 					if (h1c->px->options2 & (PR_O2_H1_ADJ_BUGCLI|PR_O2_H1_ADJ_BUGSRV))
 						h1_adjust_case_outgoing_hdr(h1s, h1m, &n);
 					if (!htx_hdr_to_h1(n, v, &tmp))
-						goto copy;
+						goto full;
 					TRACE_STATE("add \"Transfer-Encoding: chunked\"", H1_EV_TX_DATA|H1_EV_TX_HDRS, h1c->conn, h1s);
 					h1m->flags |= H1_MF_CHNK;
 				}
@@ -1712,14 +1712,14 @@
 						if (h1c->px->options2 & (PR_O2_H1_ADJ_BUGCLI|PR_O2_H1_ADJ_BUGSRV))
 							h1_adjust_case_outgoing_hdr(h1s, h1m, &n);
 						if (!htx_hdr_to_h1(n, v, &tmp))
-							goto copy;
+							goto full;
 					}
 					TRACE_STATE("add server name header", H1_EV_TX_DATA|H1_EV_TX_HDRS, h1c->conn, h1s);
 					h1s->flags |= H1S_F_HAVE_SRV_NAME;
 				}
 
 				if (!chunk_memcat(&tmp, "\r\n", 2))
-					goto copy;
+					goto full;
 
 				TRACE_PROTO((!(h1m->flags & H1_MF_RESP) ? "H1 request headers xferred" : "H1 response headers xferred"),
 					    H1_EV_TX_DATA|H1_EV_TX_HDRS, h1c->conn, h1s);
@@ -1756,7 +1756,7 @@
 					/* Chunked message without explicit trailers */
 					if (h1m->flags & H1_MF_CHNK) {
 						if (!chunk_memcat(&tmp, "0\r\n\r\n", 5))
-							goto copy;
+							goto full;
 					}
 					goto done;
 				}
@@ -1764,7 +1764,7 @@
 					/* If the message is not chunked, never
 					 * add the last chunk. */
 					if ((h1m->flags & H1_MF_CHNK) && !chunk_memcat(&tmp, "0\r\n", 3))
-						goto copy;
+						goto full;
 					TRACE_PROTO("sending message trailers", H1_EV_TX_DATA|H1_EV_TX_TLRS, h1c->conn, h1s, chn_htx);
 					goto trailers;
 				}
@@ -1775,7 +1775,7 @@
 				v = htx_get_blk_value(chn_htx, blk);
 				v.len = vlen;
 				if (!htx_data_to_h1(v, &tmp, !!(h1m->flags & H1_MF_CHNK)))
-					goto copy;
+					goto full;
 
 				if (h1m->state == H1_MSG_DATA)
 					TRACE_PROTO((!(h1m->flags & H1_MF_RESP) ? "H1 request payload data xferred" : "H1 response payload data xferred"),
@@ -1799,7 +1799,7 @@
 
 				if (type == HTX_BLK_EOT) {
 					if (!chunk_memcat(&tmp, "\r\n", 2))
-						goto copy;
+						goto full;
 					TRACE_PROTO((!(h1m->flags & H1_MF_RESP) ? "H1 request trailers xferred" : "H1 response trailers xferred"),
 						    H1_EV_TX_DATA|H1_EV_TX_TLRS, h1c->conn, h1s);
 				}
@@ -1811,7 +1811,7 @@
 					if (h1c->px->options2 & (PR_O2_H1_ADJ_BUGCLI|PR_O2_H1_ADJ_BUGSRV))
 						h1_adjust_case_outgoing_hdr(h1s, h1m, &n);
 					if (!htx_hdr_to_h1(n, v, &tmp))
-						goto copy;
+						goto full;
 				}
 				break;
 
@@ -1871,6 +1871,11 @@
   end:
 	TRACE_LEAVE(H1_EV_TX_DATA, h1c->conn, h1s, chn_htx, (size_t[]){total});
 	return total;
+
+  full:
+	TRACE_STATE("h1c obuf full", H1_EV_TX_DATA|H1_EV_H1S_BLK, h1c->conn, h1s);
+	h1c->flags |= H1C_F_OUT_FULL;
+	goto copy;
 }
 
 /*********************************************************/