diff --git a/src/mux_h1.c b/src/mux_h1.c
index a88722c6d..59784051e 100644
--- a/src/mux_h1.c
+++ b/src/mux_h1.c
@@ -1323,11 +1323,6 @@ static size_t h1_process_input(struct h1c *h1c, struct buffer *buf, int flags)
 	int errflag;
 
 	htx = htx_from_buf(buf);
-	data = htx->data;
-	count = b_data(&h1c->ibuf);
-	if (!count)
-		goto end;
-	rsv = ((flags & CO_RFL_KEEP_RSV) ? global.tune.maxrewrite : 0);
 
 	if (!conn_is_back(h1c->conn)) {
 		h1m = &h1s->req;
@@ -1338,6 +1333,12 @@ static size_t h1_process_input(struct h1c *h1c, struct buffer *buf, int flags)
 		errflag = H1S_F_RES_ERROR;
 	}
 
+	data = htx->data;
+	count = b_data(&h1c->ibuf);
+	if (!count)
+		goto end;
+	rsv = ((flags & CO_RFL_KEEP_RSV) ? global.tune.maxrewrite : 0);
+
 	do {
 		if (h1m->state <= H1_MSG_LAST_LF) {
 			ret = h1_process_headers(h1s, h1m, htx, &h1c->ibuf, &total, count);