diff --git a/src/mux_h2.c b/src/mux_h2.c
index 2129f7f07..6ecec4d62 100644
--- a/src/mux_h2.c
+++ b/src/mux_h2.c
@@ -4438,8 +4438,10 @@ static size_t h2s_htx_frt_make_resp_headers(struct h2s *h2s, struct htx *htx)
 	}
 
 	/* get the start line, we do have one */
-	sl = htx_get_stline(htx);
-	ALREADY_CHECKED(sl);
+	blk = htx_get_head_blk(htx);
+	BUG_ON(htx_get_blk_type(blk) != HTX_BLK_RES_SL);
+	ALREADY_CHECKED(blk);
+	sl = htx_get_blk_ptr(htx, blk);
 	h2s->status = sl->info.res.status;
 	if (h2s->status < 100 || h2s->status > 999)
 		goto fail;
@@ -4645,8 +4647,10 @@ static size_t h2s_htx_bck_make_req_headers(struct h2s *h2s, struct htx *htx)
 	}
 
 	/* get the start line, we do have one */
-	sl = htx_get_stline(htx);
-	ALREADY_CHECKED(sl);
+	blk = htx_get_head_blk(htx);
+	BUG_ON(htx_get_blk_type(blk) != HTX_BLK_REQ_SL);
+	ALREADY_CHECKED(blk);
+	sl = htx_get_blk_ptr(htx, blk);
 	meth = htx_sl_req_meth(sl);
 	path = htx_sl_req_uri(sl);