diff --git a/js/acutis_js.ml b/js/acutis_js.ml
index 6e7377b8..27542b66 100644
--- a/js/acutis_js.ml
+++ b/js/acutis_js.ml
@@ -99,13 +99,10 @@ module Concurrent = struct
 
   let buffer_create () = new%js Js.array_empty
 
-  let buffer_add_string (b : buffer) s =
-    b##push (promise (Js.string s)) |> ignore
-
-  let buffer_add_promise (b : buffer) p =
+  let buffer_append (b : buffer) p =
     b##push (Promise.then_ p @@ fun s -> promise (Js.string s)) |> ignore
 
-  let buffer_to_promise (b : buffer) =
+  let buffer_contents (b : buffer) =
     Promise.then_ (Promise.all b) @@ fun a ->
     promise (a##join (Js.string "") |> Js.to_string)
 end
diff --git a/lib/instruct.ml b/lib/instruct.ml
index 0a4ecba4..4e45885e 100644
--- a/lib/instruct.ml
+++ b/lib/instruct.ml
@@ -140,16 +140,14 @@ module type SEM = sig
   (** {1 Buffers.} *)
 
   type buffer
-  (** This type is not a typical "buffer" since it must work with promises. The
-      language may implement it however is most suitable. *)
+  (** A buffer of concurrent string promises. *)
 
   val buffer_create : unit -> buffer exp
-  val buffer_add_string : buffer exp -> string exp -> unit stmt
-  val buffer_add_promise : buffer exp -> string promise exp -> unit stmt
+  val buffer_append : buffer exp -> string promise exp -> unit stmt
 
   (** These are lambdas to minimize generated code. *)
 
-  val buffer_to_promise : (buffer -> string promise) exp
+  val buffer_contents : (buffer -> string promise) exp
   val escape : (string -> string) exp
 
   (** {1 Mutable stacks.} *)
@@ -278,7 +276,7 @@ end = struct
 
   type runtime = {
     comps : (data hashtbl -> string promise) hashtbl exp;
-    buffer_to_promise : (buffer -> string promise) exp;
+    buffer_contents : (buffer -> string promise) exp;
     escape : (string -> string) exp;
   }
 
@@ -289,8 +287,8 @@ end = struct
 
   let parse_escape runtime buf esc x =
     match esc with
-    | C.No_escape -> buffer_add_string buf x
-    | C.Escape -> buffer_add_string buf (runtime.escape @@ x)
+    | C.No_escape -> buffer_append buf (promise x)
+    | C.Escape -> buffer_append buf (promise (runtime.escape @@ x))
 
   let fmt runtime buf esc x = function
     | C.Fmt_string -> parse_escape runtime buf esc (Data.to_string x)
@@ -482,7 +480,7 @@ end = struct
         aux hd tl
 
   let rec node runtime buffer props = function
-    | C.Text s -> buffer_add_string buffer (string s)
+    | C.Text s -> buffer_append buffer (promise (string s))
     | C.Echo (echs, fmt, default, esc) ->
         echoes runtime buffer props esc default fmt echs
     | C.Match (blocks, data, { tree; exits }) ->
@@ -539,7 +537,7 @@ end = struct
                 s1 |: s2))
     | Component (name, _, blocks, dict) ->
         construct_blocks runtime buffer blocks props (fun blocks buffer ->
-            buffer_add_promise buffer
+            buffer_append buffer
               (runtime.comps.%{string name}
               @@ construct_data_hashtbl blocks props dict))
 
@@ -556,19 +554,17 @@ end = struct
         |> Seq.map (fun (i, block) ->
                let$ buffer = ("buffer", buffer_create ()) in
                let s1 = nodes runtime buffer props block in
-               let s2 =
-                 blocks.%(int i) <- runtime.buffer_to_promise @@ buffer
-               in
+               let s2 = blocks.%(int i) <- runtime.buffer_contents @@ buffer in
                s1 |: s2)
         |> join_stmts
       in
       let s2 =
-        buffer_add_promise buffer
+        buffer_append buffer
           (bind (promise_array blocks)
              (lambda (fun blocks_resolved ->
                   let$ buffer = ("buffer", buffer_create ()) in
                   let s1 = f blocks_resolved buffer in
-                  let s2 = return (runtime.buffer_to_promise @@ buffer) in
+                  let s2 = return (runtime.buffer_contents @@ buffer) in
                   s1 |: s2)))
       in
       s1 |: s2
@@ -1067,9 +1063,9 @@ end = struct
         compiled.C.components ([], [])
     in
     let$ escape = ("acutis_escape", escape) in
-    let$ buffer_to_promise = ("buffer_to_promise", buffer_to_promise) in
+    let$ buffer_contents = ("buffer_contents", buffer_contents) in
     let$ comps = ("components", hashtbl_create ()) in
-    let runtime = { escape; comps; buffer_to_promise } in
+    let runtime = { escape; comps; buffer_contents } in
     let s1 =
       List.to_seq externals
       |> Seq.map (fun (k, tys, v) ->
@@ -1091,7 +1087,7 @@ end = struct
                lambda (fun props ->
                    let$ buffer = ("buffer", buffer_create ()) in
                    let s1 = nodes runtime buffer props v in
-                   let s2 = return (buffer_to_promise @@ buffer) in
+                   let s2 = return (buffer_contents @@ buffer) in
                    s1 |: s2))
       |> join_stmts
     in
@@ -1150,7 +1146,7 @@ end = struct
              let s3 =
                let$ buffer = ("buffer", buffer_create ()) in
                let s1 = nodes runtime buffer props compiled.nodes in
-               let s2 = return (buffer_to_promise @@ buffer) in
+               let s2 = return (buffer_contents @@ buffer) in
                s1 |: s2
              in
              s1 |: s2 |: s3))
@@ -1270,9 +1266,8 @@ module MakeTrans
   let bind a f = fwde (F.bind (bwde a) (bwde f))
   let promise_array a = fwde (F.promise_array (bwde a))
   let buffer_create () = fwde (F.buffer_create ())
-  let buffer_add_string b s = fwds (F.buffer_add_string (bwde b) (bwde s))
-  let buffer_add_promise b p = fwds (F.buffer_add_promise (bwde b) (bwde p))
-  let buffer_to_promise = fwde F.buffer_to_promise
+  let buffer_append b s = fwds (F.buffer_append (bwde b) (bwde s))
+  let buffer_contents = fwde F.buffer_contents
   let escape = fwde F.escape
   let stack_create () = fwde (F.stack_create ())
   let stack_is_empty s = fwde (F.stack_is_empty (bwde s))
@@ -1459,9 +1454,8 @@ let pp (type a) pp_import ppf c =
     type buffer
 
     let buffer_create () = F.dprintf "(buffer_create)"
-    let buffer_add_string = F.dprintf "(@[buffer_add_string@ %t@ %t@])"
-    let buffer_add_promise = F.dprintf "(@[buffer_add_promise@ %t@ %t@])"
-    let buffer_to_promise = F.dprintf "(buffer_to_promise)"
+    let buffer_append = F.dprintf "(@[buffer_append@ %t@ %t@])"
+    let buffer_contents = F.dprintf "(buffer_contents)"
     let escape = F.dprintf "(escape)"
 
     type 'a stack
diff --git a/lib/printJs.ml b/lib/printJs.ml
index db853001..b0baa622 100644
--- a/lib/printJs.ml
+++ b/lib/printJs.ml
@@ -263,10 +263,9 @@ module MakeJavaScript (M : JSMODULE) :
   type buffer
 
   let buffer_create () = array [||]
-  let buffer_add_string b s = stmt (b.!("push") @@ s)
-  let buffer_add_promise = buffer_add_string
+  let buffer_append b s = stmt (b.!("push") @@ s)
 
-  let buffer_to_promise =
+  let buffer_contents =
     lambda (fun a ->
         return
           (bind (promise_array a)
diff --git a/lib/render.ml b/lib/render.ml
index b25eef18..2bf87d7f 100644
--- a/lib/render.ml
+++ b/lib/render.ml
@@ -16,9 +16,8 @@ module type CONCURRENT = sig
   val bind : 'a promise -> ('a -> 'b promise) -> 'b promise
   val promise_array : 'a promise array -> 'a array promise
   val buffer_create : unit -> buffer
-  val buffer_add_string : buffer -> string -> unit
-  val buffer_add_promise : buffer -> string promise -> unit
-  val buffer_to_promise : buffer -> string promise
+  val buffer_append : buffer -> string promise -> unit
+  val buffer_contents : buffer -> string promise
 end
 
 module type DECODABLE = sig
@@ -315,7 +314,6 @@ module MakeString = Make (struct
   let bind = ( |> )
   let promise_array = Fun.id
   let buffer_create () = Buffer.create 1024
-  let buffer_add_string = Buffer.add_string
-  let buffer_add_promise = Buffer.add_string
-  let buffer_to_promise = Buffer.contents
+  let buffer_append = Buffer.add_string
+  let buffer_contents = Buffer.contents
 end)
diff --git a/lib/render.mli b/lib/render.mli
index 9e03ce7b..dd7ad3fd 100644
--- a/lib/render.mli
+++ b/lib/render.mli
@@ -20,9 +20,8 @@ module type CONCURRENT = sig
   val bind : 'a promise -> ('a -> 'b promise) -> 'b promise
   val promise_array : 'a promise array -> 'a array promise
   val buffer_create : unit -> buffer
-  val buffer_add_string : buffer -> string -> unit
-  val buffer_add_promise : buffer -> string promise -> unit
-  val buffer_to_promise : buffer -> string promise
+  val buffer_append : buffer -> string promise -> unit
+  val buffer_contents : buffer -> string promise
 end
 
 module type DECODABLE = sig
diff --git a/test/parse-test.t/run.t b/test/parse-test.t/run.t
index 834c9e66..8fdb54a9 100644
--- a/test/parse-test.t/run.t
+++ b/test/parse-test.t/run.t
@@ -876,41 +876,41 @@ Print the optimized form
 Print the runtime instructions
   $ acutis template.acutis component.acutis component2.acutis --printinst
   (let$ acutis_escape/0 = (escape))
-  (let$ buffer_to_promise/0 = (buffer_to_promise))
+  (let$ buffer_contents/0 = (buffer_contents))
   (let$ components/0 = (hashtbl_create))
   (unit)
   (components/0.%{"Component2"} <-
    (lambda arg/0
     ((let$ buffer/0 = (buffer_create))
-     (buffer_add_string buffer/0
-      (acutis_escape/0 @@ (Data.to_string (arg/0.%{"children"}))))
-     (buffer_add_string buffer/0 "\n")
-     (return (buffer_to_promise/0 @@ buffer/0)))))
+     (buffer_append buffer/0
+      (promise (acutis_escape/0 @@ (Data.to_string (arg/0.%{"children"})))))
+     (buffer_append buffer/0 (promise "\n"))
+     (return (buffer_contents/0 @@ buffer/0)))))
   (components/0.%{"Component"} <-
    (lambda arg/1
     ((let$ buffer/1 = (buffer_create))
-     (buffer_add_string buffer/1
-      (acutis_escape/0 @@ (Data.to_string (arg/1.%{"a_prop"}))))
-     (buffer_add_string buffer/1 "\n")
-     (buffer_add_string buffer/1
-      (acutis_escape/0 @@ (Data.to_string (arg/1.%{"c_prop"}))))
-     (buffer_add_string buffer/1 "\n")
-     (buffer_add_string buffer/1
-      (acutis_escape/0 @@ (Data.to_string (arg/1.%{"d_prop"}))))
-     (buffer_add_string buffer/1 "\n")
-     (buffer_add_string buffer/1
-      (acutis_escape/0 @@ (Data.to_string (arg/1.%{"f_prop"}))))
-     (buffer_add_string buffer/1 "\n")
-     (buffer_add_string buffer/1
-      (acutis_escape/0 @@ (Data.to_string (arg/1.%{"g_prop"}))))
-     (buffer_add_string buffer/1 "\n")
-     (buffer_add_string buffer/1
-      (acutis_escape/0 @@ (Data.to_string (arg/1.%{"h_prop"}))))
-     (buffer_add_string buffer/1 "\n")
-     (buffer_add_string buffer/1
-      (acutis_escape/0 @@ (Data.to_string (arg/1.%{"i_prop"}))))
-     (buffer_add_string buffer/1 "\n")
-     (return (buffer_to_promise/0 @@ buffer/1)))))
+     (buffer_append buffer/1
+      (promise (acutis_escape/0 @@ (Data.to_string (arg/1.%{"a_prop"})))))
+     (buffer_append buffer/1 (promise "\n"))
+     (buffer_append buffer/1
+      (promise (acutis_escape/0 @@ (Data.to_string (arg/1.%{"c_prop"})))))
+     (buffer_append buffer/1 (promise "\n"))
+     (buffer_append buffer/1
+      (promise (acutis_escape/0 @@ (Data.to_string (arg/1.%{"d_prop"})))))
+     (buffer_append buffer/1 (promise "\n"))
+     (buffer_append buffer/1
+      (promise (acutis_escape/0 @@ (Data.to_string (arg/1.%{"f_prop"})))))
+     (buffer_append buffer/1 (promise "\n"))
+     (buffer_append buffer/1
+      (promise (acutis_escape/0 @@ (Data.to_string (arg/1.%{"g_prop"})))))
+     (buffer_append buffer/1 (promise "\n"))
+     (buffer_append buffer/1
+      (promise (acutis_escape/0 @@ (Data.to_string (arg/1.%{"h_prop"})))))
+     (buffer_append buffer/1 (promise "\n"))
+     (buffer_append buffer/1
+      (promise (acutis_escape/0 @@ (Data.to_string (arg/1.%{"i_prop"})))))
+     (buffer_append buffer/1 (promise "\n"))
+     (return (buffer_contents/0 @@ buffer/1)))))
   (export
    (lambda arg/2
     ((let$ stack/0 = (stack_create))
@@ -1725,37 +1725,41 @@ Print the runtime instructions
           @@ "{\n  a: {a: {b: string}, b: {c: false | true}},\n  a_prop: string,\n  b_prop: string,\n  c_prop: string,\n  d: string,\n  dict: <int>,\n  e: string,\n  e_prop: string,\n  ech_a: string,\n  ech_b: false | true,\n  ech_d: ?string,\n  ech_e: ?string,\n  ech_f: float,\n  ech_i: int,\n  enums: (@\"a\" | ..., @1 | ..., false | true, false | true),\n  f_prop: string,\n  list: [?string],\n  map_d: <int>,\n  map_l: [int],\n  match_a: int,\n  match_b: string,\n  numbers:\n    {\n      exp1: float,\n      exp2: float,\n      exp3: float,\n      frac: float,\n      int: int,\n      negfrac: float,\n      negint: int\n    },\n  record: {\"!#%@\": string, a: string},\n  tagged: {@tag: false} | {@tag: true, a: string},\n  trim_a: string,\n  trim_b: string,\n  trim_c: string,\n  trim_d: string,\n  trim_e: string,\n  trim_f: string,\n  trim_g: string,\n  tuple: (int, float, string)\n}")
          @@ arg/2))))
      (let$ buffer/2 = (buffer_create))
-     (buffer_add_string buffer/2 "Echoes\n")
-     (buffer_add_string buffer/2
-      (acutis_escape/0 @@ (Data.to_string (props/0.%{"ech_a"}))))
-     (buffer_add_string buffer/2 " ")
-     (buffer_add_string buffer/2
-      (acutis_escape/0 @@ (Data.to_string (Data.string "b"))))
-     (buffer_add_string buffer/2 " ")
+     (buffer_append buffer/2 (promise "Echoes\n"))
+     (buffer_append buffer/2
+      (promise (acutis_escape/0 @@ (Data.to_string (props/0.%{"ech_a"})))))
+     (buffer_append buffer/2 (promise " "))
+     (buffer_append buffer/2
+      (promise (acutis_escape/0 @@ (Data.to_string (Data.string "b")))))
+     (buffer_append buffer/2 (promise " "))
      (let$ nullable/0 = (props/0.%{"ech_d"}))
      (if (not (Data.equal nullable/0 (Data.int 0)))
       (then
-       (buffer_add_string buffer/2
-        (Data.to_string ((Data.to_array nullable/0).%(0)))))
+       (buffer_append buffer/2
+        (promise (Data.to_string ((Data.to_array nullable/0).%(0))))))
       (else
        (let$ nullable/1 = (props/0.%{"ech_e"}))
        (if (not (Data.equal nullable/1 (Data.int 0)))
         (then
-         (buffer_add_string buffer/2
-          (Data.to_string ((Data.to_array nullable/1).%(0)))))
+         (buffer_append buffer/2
+          (promise (Data.to_string ((Data.to_array nullable/1).%(0))))))
         (else
-         (buffer_add_string buffer/2 (Data.to_string (Data.string "f\"g")))))))
-     (buffer_add_string buffer/2 "\n")
-     (buffer_add_string buffer/2
-      (acutis_escape/0 @@ (int_to_string (Data.to_int (props/0.%{"ech_i"})))))
-     (buffer_add_string buffer/2 " ")
-     (buffer_add_string buffer/2
-      (acutis_escape/0
-       @@ (float_to_string (Data.to_float (props/0.%{"ech_f"})))))
-     (buffer_add_string buffer/2 " ")
-     (buffer_add_string buffer/2
-      (acutis_escape/0 @@ (bool_to_string (Data.to_int (props/0.%{"ech_b"})))))
-     (buffer_add_string buffer/2 "\n\nNumbers\n")
+         (buffer_append buffer/2
+          (promise (Data.to_string (Data.string "f\"g"))))))))
+     (buffer_append buffer/2 (promise "\n"))
+     (buffer_append buffer/2
+      (promise
+       (acutis_escape/0 @@ (int_to_string (Data.to_int (props/0.%{"ech_i"}))))))
+     (buffer_append buffer/2 (promise " "))
+     (buffer_append buffer/2
+      (promise
+       (acutis_escape/0
+        @@ (float_to_string (Data.to_float (props/0.%{"ech_f"}))))))
+     (buffer_append buffer/2 (promise " "))
+     (buffer_append buffer/2
+      (promise
+       (acutis_escape/0 @@ (bool_to_string (Data.to_int (props/0.%{"ech_b"}))))))
+     (buffer_append buffer/2 (promise "\n\nNumbers\n"))
      (let$ arg_match/0 = [(props/0.%{"numbers"})])
      (let$ props/1 = (hashtbl_copy props/0 ))
      (let& exit/0 = -1)
@@ -1784,23 +1788,23 @@ Print the runtime instructions
                   (then (unit) (exit/0 := 0)))))))))))))))
      (if (equal_int (deref exit/0) -1) (then (unit) (exit/0 := 1)))
      (if (equal_int (deref exit/0) 0) (then (unit)) (else (unit)))
-     (buffer_add_string buffer/2 "\n\nTrim")
-     (buffer_add_string buffer/2
-      (acutis_escape/0 @@ (Data.to_string (props/0.%{"trim_a"}))))
-     (buffer_add_string buffer/2
-      (acutis_escape/0 @@ (Data.to_string (props/0.%{"trim_b"}))))
-     (buffer_add_string buffer/2 " ")
-     (buffer_add_string buffer/2
-      (acutis_escape/0 @@ (Data.to_string (props/0.%{"trim_c"}))))
-     (buffer_add_string buffer/2
-      (acutis_escape/0 @@ (Data.to_string (props/0.%{"trim_d"}))))
-     (buffer_add_string buffer/2 (Data.to_string (props/0.%{"trim_e"})))
-     (buffer_add_string buffer/2 "\n")
-     (buffer_add_string buffer/2 (Data.to_string (props/0.%{"trim_f"})))
-     (buffer_add_string buffer/2 (Data.to_string (props/0.%{"trim_g"})))
-     (buffer_add_string buffer/2 "Comments\na ")
-     (buffer_add_string buffer/2 "b")
-     (buffer_add_string buffer/2 " c\n\nFlat match\n")
+     (buffer_append buffer/2 (promise "\n\nTrim"))
+     (buffer_append buffer/2
+      (promise (acutis_escape/0 @@ (Data.to_string (props/0.%{"trim_a"})))))
+     (buffer_append buffer/2
+      (promise (acutis_escape/0 @@ (Data.to_string (props/0.%{"trim_b"})))))
+     (buffer_append buffer/2 (promise " "))
+     (buffer_append buffer/2
+      (promise (acutis_escape/0 @@ (Data.to_string (props/0.%{"trim_c"})))))
+     (buffer_append buffer/2
+      (promise (acutis_escape/0 @@ (Data.to_string (props/0.%{"trim_d"})))))
+     (buffer_append buffer/2 (promise (Data.to_string (props/0.%{"trim_e"}))))
+     (buffer_append buffer/2 (promise "\n"))
+     (buffer_append buffer/2 (promise (Data.to_string (props/0.%{"trim_f"}))))
+     (buffer_append buffer/2 (promise (Data.to_string (props/0.%{"trim_g"}))))
+     (buffer_append buffer/2 (promise "Comments\na "))
+     (buffer_append buffer/2 (promise "b"))
+     (buffer_append buffer/2 (promise " c\n\nFlat match\n"))
      (let$ arg_match/1 = [(props/0.%{"match_a"})])
      (let$ props/2 = (hashtbl_copy props/0 ))
      (let& exit/1 = -1)
@@ -1818,16 +1822,16 @@ Print the runtime instructions
       (then (unit))
       (else
        (if (equal_int (deref exit/1) 1)
-        (then (buffer_add_string buffer/2 " "))
-        (else (buffer_add_string buffer/2 " ")))))
-     (buffer_add_string buffer/2 "\n\nNested match\n")
+        (then (buffer_append buffer/2 (promise " ")))
+        (else (buffer_append buffer/2 (promise " "))))))
+     (buffer_append buffer/2 (promise "\n\nNested match\n"))
      (let$ arg_match/2 = [(props/0.%{"match_b"})])
      (let$ props/3 = (hashtbl_copy props/0 ))
      (let& exit/2 = -1)
      (let$ match_arg/9 = (arg_match/2.%(0)))
      (props/3.%{"c"} <- match_arg/9)
      (exit/2 := 0)
-     (buffer_add_string buffer/2 "\n  ")
+     (buffer_append buffer/2 (promise "\n  "))
      (let$ arg_match/3 = [(props/3.%{"d"}), (props/3.%{"e"})])
      (let$ props/4 = (hashtbl_copy props/3 ))
      (let& exit/3 = -1)
@@ -1836,18 +1840,18 @@ Print the runtime instructions
      (props/4.%{"f"} <- match_arg/10)
      (props/4.%{"g"} <- match_arg/11)
      (exit/3 := 0)
-     (buffer_add_string buffer/2 " ")
-     (buffer_add_string buffer/2
-      (acutis_escape/0 @@ (Data.to_string (props/4.%{"c"}))))
-     (buffer_add_string buffer/2 " ")
-     (buffer_add_string buffer/2
-      (acutis_escape/0 @@ (Data.to_string (props/4.%{"f"}))))
-     (buffer_add_string buffer/2 " ")
-     (buffer_add_string buffer/2
-      (acutis_escape/0 @@ (Data.to_string (props/4.%{"g"}))))
-     (buffer_add_string buffer/2 " ")
-     (buffer_add_string buffer/2 "\n")
-     (buffer_add_string buffer/2 "\n\nMap list\n")
+     (buffer_append buffer/2 (promise " "))
+     (buffer_append buffer/2
+      (promise (acutis_escape/0 @@ (Data.to_string (props/4.%{"c"})))))
+     (buffer_append buffer/2 (promise " "))
+     (buffer_append buffer/2
+      (promise (acutis_escape/0 @@ (Data.to_string (props/4.%{"f"})))))
+     (buffer_append buffer/2 (promise " "))
+     (buffer_append buffer/2
+      (promise (acutis_escape/0 @@ (Data.to_string (props/4.%{"g"})))))
+     (buffer_append buffer/2 (promise " "))
+     (buffer_append buffer/2 (promise "\n"))
+     (buffer_append buffer/2 (promise "\n\nMap list\n"))
      (let& index/0 = 0)
      (let& cell/0 = (props/0.%{"map_l"}))
      (while (not (Data.equal (deref cell/0) (Data.int 0)))
@@ -1869,14 +1873,15 @@ Print the runtime instructions
         (else
          (if (equal_int (deref exit/4) 1)
           (then
-           (buffer_add_string buffer/2 " ")
-           (buffer_add_string buffer/2
-            (acutis_escape/0 @@ (int_to_string (Data.to_int (props/5.%{"i"})))))
-           (buffer_add_string buffer/2 " "))
-          (else (buffer_add_string buffer/2 " ")))))
+           (buffer_append buffer/2 (promise " "))
+           (buffer_append buffer/2
+            (promise
+             (acutis_escape/0 @@ (int_to_string (Data.to_int (props/5.%{"i"}))))))
+           (buffer_append buffer/2 (promise " ")))
+          (else (buffer_append buffer/2 (promise " "))))))
        (incr index/0)
        (cell/0 := (list/0.%(1)))))
-     (buffer_add_string buffer/2 "\n\nMap dict\n")
+     (buffer_append buffer/2 (promise "\n\nMap dict\n"))
      (let$ match_arg/12 = (props/0.%{"map_d"}))
      (hashtbl_iter (Data.to_hashtbl match_arg/12) key/6 value/6
       (let$ props/6 = (hashtbl_copy props/0 )) (let& exit/5 = -1)
@@ -1894,16 +1899,16 @@ Print the runtime instructions
        (else
         (if (equal_int (deref exit/5) 1)
          (then
-          (buffer_add_string buffer/2 " ")
-          (buffer_add_string buffer/2
-           (acutis_escape/0 @@ (Data.to_string (props/6.%{"k"}))))
-          (buffer_add_string buffer/2 " "))
-         (else (buffer_add_string buffer/2 "\n"))))))
-     (buffer_add_string buffer/2 "\n\nComponent with props\n")
+          (buffer_append buffer/2 (promise " "))
+          (buffer_append buffer/2
+           (promise (acutis_escape/0 @@ (Data.to_string (props/6.%{"k"})))))
+          (buffer_append buffer/2 (promise " ")))
+         (else (buffer_append buffer/2 (promise "\n")))))))
+     (buffer_append buffer/2 (promise "\n\nComponent with props\n"))
      (let$ blocks/0 = (array_init 3 (promise "")))
      (let$ buffer/3 = (buffer_create))
-     (buffer_add_string buffer/3 " ")
-     (blocks/0.%(0) <- (buffer_to_promise/0 @@ buffer/3))
+     (buffer_append buffer/3 (promise " "))
+     (blocks/0.%(0) <- (buffer_contents/0 @@ buffer/3))
      (let$ buffer/4 = (buffer_create))
      (let$ arg_match/4 = [(props/0.%{"a_prop"})])
      (let$ props/7 = (hashtbl_copy props/0 ))
@@ -1911,19 +1916,19 @@ Print the runtime instructions
      (let$ match_arg/13 = (arg_match/4.%(0)))
      (props/7.%{"b_prop"} <- match_arg/13)
      (exit/6 := 0)
-     (buffer_add_string buffer/4 " ")
-     (buffer_add_string buffer/4
-      (acutis_escape/0 @@ (Data.to_string (props/7.%{"b_prop"}))))
-     (buffer_add_string buffer/4 " ")
-     (blocks/0.%(1) <- (buffer_to_promise/0 @@ buffer/4))
+     (buffer_append buffer/4 (promise " "))
+     (buffer_append buffer/4
+      (promise (acutis_escape/0 @@ (Data.to_string (props/7.%{"b_prop"})))))
+     (buffer_append buffer/4 (promise " "))
+     (blocks/0.%(1) <- (buffer_contents/0 @@ buffer/4))
      (let$ buffer/5 = (buffer_create))
      (unit)
-     (blocks/0.%(2) <- (buffer_to_promise/0 @@ buffer/5))
-     (buffer_add_promise buffer/2
+     (blocks/0.%(2) <- (buffer_contents/0 @@ buffer/5))
+     (buffer_append buffer/2
       (bind (promise_array blocks/0)
        (lambda arg/6
         ((let$ buffer/6 = (buffer_create))
-         (buffer_add_promise buffer/6
+         (buffer_append buffer/6
           ((components/0.%{"Component"})
            @@ (hashtbl
                [("a_prop", (props/0.%{"b_prop"})),
@@ -1933,21 +1938,21 @@ Print the runtime instructions
                 ("g_prop", (Data.string (arg/6.%(0)))),
                 ("h_prop", (Data.string (arg/6.%(1)))),
                 ("i_prop", (Data.string (arg/6.%(2))))])))
-         (return (buffer_to_promise/0 @@ buffer/6))))))
-     (buffer_add_string buffer/2 "\n\nComponent with implicit children\n")
+         (return (buffer_contents/0 @@ buffer/6))))))
+     (buffer_append buffer/2 (promise "\n\nComponent with implicit children\n"))
      (let$ blocks/1 = (array_init 1 (promise "")))
      (let$ buffer/7 = (buffer_create))
-     (buffer_add_string buffer/7 " ")
-     (blocks/1.%(0) <- (buffer_to_promise/0 @@ buffer/7))
-     (buffer_add_promise buffer/2
+     (buffer_append buffer/7 (promise " "))
+     (blocks/1.%(0) <- (buffer_contents/0 @@ buffer/7))
+     (buffer_append buffer/2
       (bind (promise_array blocks/1)
        (lambda arg/7
         ((let$ buffer/8 = (buffer_create))
-         (buffer_add_promise buffer/8
+         (buffer_append buffer/8
           ((components/0.%{"Component2"})
            @@ (hashtbl [("children", (Data.string (arg/7.%(0))))])))
-         (return (buffer_to_promise/0 @@ buffer/8))))))
-     (buffer_add_string buffer/2 "\n\nPatterns\n\nTuple:\n")
+         (return (buffer_contents/0 @@ buffer/8))))))
+     (buffer_append buffer/2 (promise "\n\nPatterns\n\nTuple:\n"))
      (let$ arg_match/5 = [(props/0.%{"tuple"})])
      (let$ props/8 = (hashtbl_copy props/0 ))
      (let& exit/7 = -1)
@@ -1963,9 +1968,9 @@ Print the runtime instructions
           (then (unit) (exit/7 := 0)))))))
      (if (equal_int (deref exit/7) -1) (then (unit) (exit/7 := 1)))
      (if (equal_int (deref exit/7) 0)
-      (then (buffer_add_string buffer/2 " "))
-      (else (buffer_add_string buffer/2 " ")))
-     (buffer_add_string buffer/2 "\n\nList:\n")
+      (then (buffer_append buffer/2 (promise " ")))
+      (else (buffer_append buffer/2 (promise " "))))
+     (buffer_append buffer/2 (promise "\n\nList:\n"))
      (let$ arg_match/6 = [(props/0.%{"list"})])
      (let$ props/9 = (hashtbl_copy props/0 ))
      (let& exit/8 = -1)
@@ -2010,16 +2015,16 @@ Print the runtime instructions
            (props/9.%{"_z"} <- match_arg/40)
            (exit/8 := 2)))))))
      (if (equal_int (deref exit/8) 0)
-      (then (buffer_add_string buffer/2 "\n"))
+      (then (buffer_append buffer/2 (promise "\n")))
       (else
        (if (equal_int (deref exit/8) 1)
         (then
-         (buffer_add_string buffer/2 " ")
-         (buffer_add_string buffer/2
-          (acutis_escape/0 @@ (Data.to_string (props/9.%{"a"}))))
-         (buffer_add_string buffer/2 "\n"))
-        (else (buffer_add_string buffer/2 "\n")))))
-     (buffer_add_string buffer/2 "\n\nRecord:\n")
+         (buffer_append buffer/2 (promise " "))
+         (buffer_append buffer/2
+          (promise (acutis_escape/0 @@ (Data.to_string (props/9.%{"a"})))))
+         (buffer_append buffer/2 (promise "\n")))
+        (else (buffer_append buffer/2 (promise "\n"))))))
+     (buffer_append buffer/2 (promise "\n\nRecord:\n"))
      (let$ arg_match/7 = [(props/0.%{"record"})])
      (let$ props/10 = (hashtbl_copy props/0 ))
      (let& exit/9 = -1)
@@ -2032,15 +2037,15 @@ Print the runtime instructions
      (if (equal_int (deref exit/9) -1) (then (unit) (exit/9 := 1)))
      (if (equal_int (deref exit/9) 0)
       (then
-       (buffer_add_string buffer/2 " ")
-       (buffer_add_string buffer/2
-        (acutis_escape/0 @@ (Data.to_string (props/10.%{"a"}))))
-       (buffer_add_string buffer/2 " ")
-       (buffer_add_string buffer/2
-        (acutis_escape/0 @@ (Data.to_string (props/10.%{"b"}))))
-       (buffer_add_string buffer/2 " "))
-      (else (buffer_add_string buffer/2 " ")))
-     (buffer_add_string buffer/2 "\n\nEnum:\n")
+       (buffer_append buffer/2 (promise " "))
+       (buffer_append buffer/2
+        (promise (acutis_escape/0 @@ (Data.to_string (props/10.%{"a"})))))
+       (buffer_append buffer/2 (promise " "))
+       (buffer_append buffer/2
+        (promise (acutis_escape/0 @@ (Data.to_string (props/10.%{"b"})))))
+       (buffer_append buffer/2 (promise " ")))
+      (else (buffer_append buffer/2 (promise " "))))
+     (buffer_append buffer/2 (promise "\n\nEnum:\n"))
      (let$ arg_match/8 = [(props/0.%{"enums"})])
      (let$ props/11 = (hashtbl_copy props/0 ))
      (let& exit/10 = -1)
@@ -2059,9 +2064,9 @@ Print the runtime instructions
             (then (unit) (exit/10 := 0)))))))))
      (if (equal_int (deref exit/10) -1) (then (unit) (exit/10 := 1)))
      (if (equal_int (deref exit/10) 0)
-      (then (buffer_add_string buffer/2 " "))
-      (else (buffer_add_string buffer/2 " ")))
-     (buffer_add_string buffer/2 "\n\nTagged union:\n")
+      (then (buffer_append buffer/2 (promise " ")))
+      (else (buffer_append buffer/2 (promise " "))))
+     (buffer_append buffer/2 (promise "\n\nTagged union:\n"))
      (let$ arg_match/9 = [(props/0.%{"tagged"})])
      (let$ props/12 = (hashtbl_copy props/0 ))
      (let& exit/11 = -1)
@@ -2077,12 +2082,12 @@ Print the runtime instructions
          (exit/11 := 0)))))
      (if (equal_int (deref exit/11) 0)
       (then
-       (buffer_add_string buffer/2 " ")
-       (buffer_add_string buffer/2
-        (acutis_escape/0 @@ (Data.to_string (props/12.%{"a"}))))
-       (buffer_add_string buffer/2 " "))
-      (else (buffer_add_string buffer/2 "\n")))
-     (buffer_add_string buffer/2 "\n\nDictionary:\n")
+       (buffer_append buffer/2 (promise " "))
+       (buffer_append buffer/2
+        (promise (acutis_escape/0 @@ (Data.to_string (props/12.%{"a"})))))
+       (buffer_append buffer/2 (promise " ")))
+      (else (buffer_append buffer/2 (promise "\n"))))
+     (buffer_append buffer/2 (promise "\n\nDictionary:\n"))
      (let$ arg_match/10 = [(props/0.%{"dict"})])
      (let$ props/13 = (hashtbl_copy props/0 ))
      (let& exit/12 = -1)
@@ -2099,9 +2104,10 @@ Print the runtime instructions
             (then (unit) (exit/12 := 0)))))))))
      (if (equal_int (deref exit/12) -1) (then (unit) (exit/12 := 1)))
      (if (equal_int (deref exit/12) 0)
-      (then (buffer_add_string buffer/2 " "))
-      (else (buffer_add_string buffer/2 " ")))
-     (buffer_add_string buffer/2 "\n\n! and . precedence works correctly\n")
+      (then (buffer_append buffer/2 (promise " ")))
+      (else (buffer_append buffer/2 (promise " "))))
+     (buffer_append buffer/2
+      (promise "\n\n! and . precedence works correctly\n"))
      (let$ arg_match/11 =
       [(Data.array
         [(Data.array
@@ -2123,8 +2129,9 @@ Print the runtime instructions
           (then (unit) (exit/13 := 0)))))
        (if (equal_int (deref exit/13) -1) (then (unit) (exit/13 := 1)))))
      (if (equal_int (deref exit/13) 0) (then (unit)) (else (unit)))
-     (buffer_add_string buffer/2
-      "\n\nOther syntax features\n\nPatterns with }} parse correctly:\n")
+     (buffer_append buffer/2
+      (promise
+       "\n\nOther syntax features\n\nPatterns with }} parse correctly:\n"))
      (let$ arg_match/12 = [(props/0.%{"a"})])
      (let$ props/15 = (hashtbl_copy props/0 ))
      (let& exit/14 = -1)
@@ -2133,11 +2140,11 @@ Print the runtime instructions
      (let$ match_arg/35 = ((Data.to_hashtbl match_arg/34).%{"b"}))
      (props/15.%{"b"} <- match_arg/35)
      (exit/14 := 0)
-     (buffer_add_string buffer/2 " ")
-     (buffer_add_string buffer/2
-      (acutis_escape/0 @@ (Data.to_string (props/15.%{"b"}))))
-     (buffer_add_string buffer/2 " ")
-     (buffer_add_string buffer/2 "\n\nTrailing commas parse correctly:\n")
+     (buffer_append buffer/2 (promise " "))
+     (buffer_append buffer/2
+      (promise (acutis_escape/0 @@ (Data.to_string (props/15.%{"b"})))))
+     (buffer_append buffer/2 (promise " "))
+     (buffer_append buffer/2 (promise "\n\nTrailing commas parse correctly:\n"))
      (let$ arg_match/13 =
       [(Data.hashtbl
         (hashtbl
@@ -2151,9 +2158,9 @@ Print the runtime instructions
      (let$ match_arg/36 = (arg_match/13.%(0)))
      (unit)
      (exit/15 := 0)
-     (buffer_add_string buffer/2 " ")
-     (buffer_add_string buffer/2 "\n\nStrings may contain line breaks:\n")
-     (buffer_add_string buffer/2
-      (acutis_escape/0 @@ (Data.to_string (Data.string "a\nb"))))
-     (buffer_add_string buffer/2 "\n")
-     (return (buffer_to_promise/0 @@ buffer/2)))))
+     (buffer_append buffer/2 (promise " "))
+     (buffer_append buffer/2 (promise "\n\nStrings may contain line breaks:\n"))
+     (buffer_append buffer/2
+      (promise (acutis_escape/0 @@ (Data.to_string (Data.string "a\nb")))))
+     (buffer_append buffer/2 (promise "\n"))
+     (return (buffer_contents/0 @@ buffer/2)))))
diff --git a/test/printjs/esm-cjs.t/run.t b/test/printjs/esm-cjs.t/run.t
index 586836fd..c17bff13 100644
--- a/test/printjs/esm-cjs.t/run.t
+++ b/test/printjs/esm-cjs.t/run.t
@@ -22,7 +22,7 @@
       }
       return (result$0);
     };
-  let buffer_to_promise$0 =
+  let buffer_contents$0 =
     (arg$0) => {
       return (
         Promise.all(arg$0).then((arg$1) => { return (arg$1.join("")); })
@@ -108,8 +108,8 @@
     let blocks$0 =
       Array.from({length: 1}, (arg$1) => { return (Promise.resolve("")); });
     let buffer$1 = [];
-    buffer$1.push(" text ");
-    blocks$0[0] = buffer_to_promise$0(buffer$1);
+    buffer$1.push(Promise.resolve(" text "));
+    blocks$0[0] = buffer_contents$0(buffer$1);
     buffer$0.push(
       Promise.all(blocks$0).then(
         (arg$1) => {
@@ -119,12 +119,12 @@
               new Map([["children", arg$1[0]]])
             )
           );
-          return (buffer_to_promise$0(buffer$2));
+          return (buffer_contents$0(buffer$2));
         }
       )
     );
-    buffer$0.push("\n");
-    return (buffer_to_promise$0(buffer$0));
+    buffer$0.push(Promise.resolve("\n"));
+    return (buffer_contents$0(buffer$0));
   };
 
   $ acutis \
@@ -151,7 +151,7 @@
       }
       return (result$0);
     };
-  let buffer_to_promise$0 =
+  let buffer_contents$0 =
     (arg$0) => {
       return (
         Promise.all(arg$0).then((arg$1) => { return (arg$1.join("")); })
@@ -238,8 +238,8 @@
       let blocks$0 =
         Array.from({length: 1}, (arg$1) => { return (Promise.resolve("")); });
       let buffer$1 = [];
-      buffer$1.push(" text ");
-      blocks$0[0] = buffer_to_promise$0(buffer$1);
+      buffer$1.push(Promise.resolve(" text "));
+      blocks$0[0] = buffer_contents$0(buffer$1);
       buffer$0.push(
         Promise.all(blocks$0).then(
           (arg$1) => {
@@ -249,10 +249,10 @@
                 new Map([["children", arg$1[0]]])
               )
             );
-            return (buffer_to_promise$0(buffer$2));
+            return (buffer_contents$0(buffer$2));
           }
         )
       );
-      buffer$0.push("\n");
-      return (buffer_to_promise$0(buffer$0));
+      buffer$0.push(Promise.resolve("\n"));
+      return (buffer_contents$0(buffer$0));
     };
diff --git a/test/printjs/printjs.t/run.t b/test/printjs/printjs.t/run.t
index 566759e6..d76f96ba 100644
--- a/test/printjs/printjs.t/run.t
+++ b/test/printjs/printjs.t/run.t
@@ -29,7 +29,7 @@
       }
       return (result$0);
     };
-  let buffer_to_promise$0 =
+  let buffer_contents$0 =
     (arg$0) => {
       return (
         Promise.all(arg$0).then((arg$1) => { return (arg$1.join("")); })
@@ -263,11 +263,13 @@
       let buffer$0 = [];
       let nullable$0 = arg$0.get("optional");
       if (!(nullable$0 === 0)) {
-        buffer$0.push(acutis_escape$0(nullable$0[0].toString()));
+        buffer$0.push(
+          Promise.resolve(acutis_escape$0(nullable$0[0].toString()))
+        );
       } else {
-        buffer$0.push(acutis_escape$0(arg$0.get("children")));
+        buffer$0.push(Promise.resolve(acutis_escape$0(arg$0.get("children"))));
       }
-      buffer$0.push("\n");
+      buffer$0.push(Promise.resolve("\n"));
       let index$0 = 0;
       let cell$0 = arg$0.get("list");
       while (!(cell$0 === 0)) {
@@ -276,11 +278,13 @@
         let exit$0 = -1;
         props$0.set("i", head$0);
         exit$0 = 0;
-        buffer$0.push(acutis_escape$0(props$0.get("i").toString()));
+        buffer$0.push(
+          Promise.resolve(acutis_escape$0(props$0.get("i").toString()))
+        );
         index$0++;
         cell$0 = cell$0[1];
       }
-      return (buffer_to_promise$0(buffer$0));
+      return (buffer_contents$0(buffer$0));
     }
   );
   export default (arg$0) => {
@@ -1329,41 +1333,55 @@
       );
     }
     let buffer$0 = [];
-    buffer$0.push("Formatters\n----------\n\n%i    ");
-    buffer$0.push(acutis_escape$0(props$0.get("big_int").toString()));
-    buffer$0.push("\n%f    ");
-    buffer$0.push(acutis_escape$0(props$0.get("big_float").toString()));
-    buffer$0.push("\n%b    ");
-    buffer$0.push(acutis_escape$0(props$0.get("bool1") ? "true" : "false"));
-    buffer$0.push("\n%b    ");
-    buffer$0.push(acutis_escape$0(props$0.get("bool2") ? "true" : "false"));
-    buffer$0.push("\n\nEscaping\n--------\n\nEscaped     ");
-    buffer$0.push(acutis_escape$0(props$0.get("dangerous")));
-    buffer$0.push("\nNot escaped ");
-    buffer$0.push(props$0.get("dangerous"));
-    buffer$0.push("\n\nNullable echo chaining\n----------------------\n\n");
+    buffer$0.push(Promise.resolve("Formatters\n----------\n\n%i    "));
+    buffer$0.push(
+      Promise.resolve(acutis_escape$0(props$0.get("big_int").toString()))
+    );
+    buffer$0.push(Promise.resolve("\n%f    "));
+    buffer$0.push(
+      Promise.resolve(acutis_escape$0(props$0.get("big_float").toString()))
+    );
+    buffer$0.push(Promise.resolve("\n%b    "));
+    buffer$0.push(
+      Promise.resolve(acutis_escape$0(props$0.get("bool1") ? "true" : "false"))
+    );
+    buffer$0.push(Promise.resolve("\n%b    "));
+    buffer$0.push(
+      Promise.resolve(acutis_escape$0(props$0.get("bool2") ? "true" : "false"))
+    );
+    buffer$0.push(Promise.resolve("\n\nEscaping\n--------\n\nEscaped     "));
+    buffer$0.push(Promise.resolve(acutis_escape$0(props$0.get("dangerous"))));
+    buffer$0.push(Promise.resolve("\nNot escaped "));
+    buffer$0.push(Promise.resolve(props$0.get("dangerous")));
+    buffer$0.push(
+      Promise.resolve("\n\nNullable echo chaining\n----------------------\n\n")
+    );
     let nullable$0 = props$0.get("null_int");
     if (!(nullable$0 === 0)) {
-      buffer$0.push(acutis_escape$0(nullable$0[0].toString()));
+      buffer$0.push(Promise.resolve(acutis_escape$0(nullable$0[0].toString())));
     } else {
       let nullable$1 = props$0.get("null_float");
       if (!(nullable$1 === 0)) {
-        buffer$0.push(acutis_escape$0(nullable$1[0].toString()));
+        buffer$0.push(
+          Promise.resolve(acutis_escape$0(nullable$1[0].toString()))
+        );
       } else {
         let nullable$2 = props$0.get("null_bool");
         if (!(nullable$2 === 0)) {
-          buffer$0.push(acutis_escape$0(nullable$2[0] ? "true" : "false"));
+          buffer$0.push(
+            Promise.resolve(acutis_escape$0(nullable$2[0] ? "true" : "false"))
+          );
         } else {
           let nullable$3 = props$0.get("null_string");
           if (!(nullable$3 === 0)) {
-            buffer$0.push(acutis_escape$0(nullable$3[0]));
+            buffer$0.push(Promise.resolve(acutis_escape$0(nullable$3[0])));
           } else {
-            buffer$0.push(acutis_escape$0("pass"));
+            buffer$0.push(Promise.resolve(acutis_escape$0("pass")));
           }
         }
       }
     }
-    buffer$0.push("\n\nMatching\n--------\n\n");
+    buffer$0.push(Promise.resolve("\n\nMatching\n--------\n\n"));
     let arg_match$0 = [props$0.get("record").get("int_enum")];
     let props$1 = new Map(props$0);
     let exit$0 = -1;
@@ -1373,7 +1391,11 @@
     } else {
       if (match_arg$0 === 40) { exit$0 = 1; }
     }
-    if (exit$0 === 0) { buffer$0.push("8\n"); } else { buffer$0.push("40\n"); }
+    if (exit$0 === 0) {
+      buffer$0.push(Promise.resolve("8\n"));
+    } else {
+      buffer$0.push(Promise.resolve("40\n"));
+    }
     let arg_match$1 = [props$0.get("record")];
     let props$2 = new Map(props$0);
     let exit$1 = -1;
@@ -1385,9 +1407,9 @@
       if (match_arg$2 === "yes") { exit$1 = 0; }
     }
     if (exit$1 === 0) {
-      buffer$0.push("yes\n");
+      buffer$0.push(Promise.resolve("yes\n"));
     } else {
-      buffer$0.push("no\n");
+      buffer$0.push(Promise.resolve("no\n"));
     }
     let arg_match$2 = [props$0.get("tagged_record_bool")];
     let props$3 = new Map(props$0);
@@ -1406,11 +1428,13 @@
       }
     }
     if (exit$2 === 0) {
-      buffer$0.push(acutis_escape$0(props$3.get("a")));
-      buffer$0.push("\n");
+      buffer$0.push(Promise.resolve(acutis_escape$0(props$3.get("a"))));
+      buffer$0.push(Promise.resolve("\n"));
     } else {
-      buffer$0.push(acutis_escape$0(props$3.get("b").toString()));
-      buffer$0.push("\n");
+      buffer$0.push(
+        Promise.resolve(acutis_escape$0(props$3.get("b").toString()))
+      );
+      buffer$0.push(Promise.resolve("\n"));
     }
     let arg_match$3 = [props$0.get("tagged_record_int")];
     let props$4 = new Map(props$0);
@@ -1432,14 +1456,18 @@
       }
     }
     if (exit$3 === 0) {
-      buffer$0.push("Fail\n");
+      buffer$0.push(Promise.resolve("Fail\n"));
     } else {
-      buffer$0.push(acutis_escape$0(props$4.get("a").toString()));
-      buffer$0.push(" ");
-      buffer$0.push(acutis_escape$0(props$4.get("b")));
-      buffer$0.push(" ");
-      buffer$0.push(acutis_escape$0(props$4.get("c") ? "true" : "false"));
-      buffer$0.push("\n");
+      buffer$0.push(
+        Promise.resolve(acutis_escape$0(props$4.get("a").toString()))
+      );
+      buffer$0.push(Promise.resolve(" "));
+      buffer$0.push(Promise.resolve(acutis_escape$0(props$4.get("b"))));
+      buffer$0.push(Promise.resolve(" "));
+      buffer$0.push(
+        Promise.resolve(acutis_escape$0(props$4.get("c") ? "true" : "false"))
+      );
+      buffer$0.push(Promise.resolve("\n"));
     }
     let arg_match$4 = [props$0.get("tagged_record_open")];
     let props$5 = new Map(props$0);
@@ -1453,13 +1481,13 @@
     }
     if (exit$4 === -1) { exit$4 = 1; }
     if (exit$4 === 0) {
-      buffer$0.push(" ");
-      buffer$0.push(acutis_escape$0(props$5.get("b")));
-      buffer$0.push("\n");
+      buffer$0.push(Promise.resolve(" "));
+      buffer$0.push(Promise.resolve(acutis_escape$0(props$5.get("b"))));
+      buffer$0.push(Promise.resolve("\n"));
     } else {
-      buffer$0.push("Another tag!\n");
+      buffer$0.push(Promise.resolve("Another tag!\n"));
     }
-    buffer$0.push("\n\nMapping\n-------\n\n");
+    buffer$0.push(Promise.resolve("\n\nMapping\n-------\n\n"));
     let match_arg$9 = props$0.get("null_string_dict");
     for (let x$0 of match_arg$9) {
       let props$6 = new Map(props$0);
@@ -1474,13 +1502,13 @@
         exit$5 = 1;
       }
       if (exit$5 === 0) {
-        buffer$0.push(acutis_escape$0(props$6.get("key")));
-        buffer$0.push(" is null.\n");
+        buffer$0.push(Promise.resolve(acutis_escape$0(props$6.get("key"))));
+        buffer$0.push(Promise.resolve(" is null.\n"));
       } else {
-        buffer$0.push(acutis_escape$0(props$6.get("key")));
-        buffer$0.push(" is ");
-        buffer$0.push(acutis_escape$0(props$6.get("str")));
-        buffer$0.push("\n");
+        buffer$0.push(Promise.resolve(acutis_escape$0(props$6.get("key"))));
+        buffer$0.push(Promise.resolve(" is "));
+        buffer$0.push(Promise.resolve(acutis_escape$0(props$6.get("str"))));
+        buffer$0.push(Promise.resolve("\n"));
       }
     }
     let index$0 = 0;
@@ -1491,8 +1519,10 @@
       let exit$5 = -1;
       props$6.set("i", head$0);
       exit$5 = 0;
-      buffer$0.push(acutis_escape$0(props$6.get("i").toString()));
-      buffer$0.push("\n");
+      buffer$0.push(
+        Promise.resolve(acutis_escape$0(props$6.get("i").toString()))
+      );
+      buffer$0.push(Promise.resolve("\n"));
       index$0++;
       cell$0 = cell$0[1];
     }
@@ -1505,10 +1535,14 @@
       props$6.set("i", head$0);
       props$6.set("key", index$1);
       exit$5 = 0;
-      buffer$0.push(acutis_escape$0(props$6.get("key").toString()));
-      buffer$0.push(" : ");
-      buffer$0.push(acutis_escape$0(props$6.get("i").toString()));
-      buffer$0.push("\n");
+      buffer$0.push(
+        Promise.resolve(acutis_escape$0(props$6.get("key").toString()))
+      );
+      buffer$0.push(Promise.resolve(" : "));
+      buffer$0.push(
+        Promise.resolve(acutis_escape$0(props$6.get("i").toString()))
+      );
+      buffer$0.push(Promise.resolve("\n"));
       index$1++;
       cell$1 = cell$1[1];
     }
@@ -1536,8 +1570,10 @@
           let exit$7 = -1;
           props$8.set("i", head$2);
           exit$7 = 0;
-          buffer$0.push(acutis_escape$0(props$8.get("i").toString()));
-          buffer$0.push(" ");
+          buffer$0.push(
+            Promise.resolve(acutis_escape$0(props$8.get("i").toString()))
+          );
+          buffer$0.push(Promise.resolve(" "));
           index$4++;
           cell$4 = cell$4[1];
         }
@@ -1547,7 +1583,7 @@
       index$2++;
       cell$2 = cell$2[1];
     }
-    buffer$0.push("\n\n");
+    buffer$0.push(Promise.resolve("\n\n"));
     let index$3 = 0;
     let cell$3 = props$0.get("nested_nullable_list");
     while (!(cell$3 === 0)) {
@@ -1568,26 +1604,34 @@
         }
       }
       if (exit$5 === 0) {
-        buffer$0.push("Level 1 null\n");
+        buffer$0.push(Promise.resolve("Level 1 null\n"));
       } else {
         if (exit$5 === 1) {
-          buffer$0.push("Level 2 null (This shouldn't render.)\n");
+          buffer$0.push(
+            Promise.resolve("Level 2 null (This shouldn't render.)\n")
+          );
         } else {
-          buffer$0.push("Level 3 ");
-          buffer$0.push(acutis_escape$0(props$6.get("b") ? "true" : "false"));
-          buffer$0.push("\n");
+          buffer$0.push(Promise.resolve("Level 3 "));
+          buffer$0.push(
+            Promise.resolve(
+              acutis_escape$0(props$6.get("b") ? "true" : "false")
+            )
+          );
+          buffer$0.push(Promise.resolve("\n"));
         }
       }
       index$3++;
       cell$3 = cell$3[1];
     }
     buffer$0.push(
-      "\n\
+      Promise.resolve(
+        "\n\
   \n\
   Dictionaries match correctly\n\
   ----------------------------\n\
   \n\
   "
+      )
     );
     let arg_match$5 = [props$0.get("null_string_dict")];
     let props$6 = new Map(props$0);
@@ -1635,19 +1679,19 @@
     }
     if (exit$5 === -1) { exit$5 = 3; }
     if (exit$5 === 0) {
-      buffer$0.push(" ");
-      buffer$0.push(acutis_escape$0(props$6.get("a")));
-      buffer$0.push(" ");
-      buffer$0.push(acutis_escape$0(props$6.get("b")));
-      buffer$0.push("\n");
+      buffer$0.push(Promise.resolve(" "));
+      buffer$0.push(Promise.resolve(acutis_escape$0(props$6.get("a"))));
+      buffer$0.push(Promise.resolve(" "));
+      buffer$0.push(Promise.resolve(acutis_escape$0(props$6.get("b"))));
+      buffer$0.push(Promise.resolve("\n"));
     } else {
       if (exit$5 === 1) {
-        buffer$0.push(" Fail.\n");
+        buffer$0.push(Promise.resolve(" Fail.\n"));
       } else {
         if (exit$5 === 2) {
-          buffer$0.push(" Pass.\n");
+          buffer$0.push(Promise.resolve(" Pass.\n"));
         } else {
-          buffer$0.push(" Fail.\n");
+          buffer$0.push(Promise.resolve(" Fail.\n"));
         }
       }
     }
@@ -1686,39 +1730,41 @@
     }
     if (exit$6 === -1) { exit$6 = 3; }
     if (exit$6 === 0) {
-      buffer$0.push(" Fail. ");
-      buffer$0.push(acutis_escape$0(props$7.get("a")));
-      buffer$0.push(" ");
-      buffer$0.push(acutis_escape$0(props$7.get("b")));
-      buffer$0.push("\n");
+      buffer$0.push(Promise.resolve(" Fail. "));
+      buffer$0.push(Promise.resolve(acutis_escape$0(props$7.get("a"))));
+      buffer$0.push(Promise.resolve(" "));
+      buffer$0.push(Promise.resolve(acutis_escape$0(props$7.get("b"))));
+      buffer$0.push(Promise.resolve("\n"));
     } else {
       if (exit$6 === 1) {
-        buffer$0.push(" Fail.\n");
+        buffer$0.push(Promise.resolve(" Fail.\n"));
       } else {
         if (exit$6 === 2) {
-          buffer$0.push(" Pass.\n");
+          buffer$0.push(Promise.resolve(" Pass.\n"));
         } else {
-          buffer$0.push(" Fail.\n");
+          buffer$0.push(Promise.resolve(" Fail.\n"));
         }
       }
     }
     buffer$0.push(
-      "\n\nConstructing async blocks\n-------------------------\n\n"
+      Promise.resolve(
+        "\n\nConstructing async blocks\n-------------------------\n\n"
+      )
     );
     let blocks$0 =
       Array.from({length: 2}, (arg$1) => { return (Promise.resolve("")); });
     let buffer$1 = [];
-    buffer$1.push(" Nested block ");
+    buffer$1.push(Promise.resolve(" Nested block "));
     let nullable$1 = props$0.get("null_string");
     if (!(nullable$1 === 0)) {
-      buffer$1.push(acutis_escape$0(nullable$1[0]));
+      buffer$1.push(Promise.resolve(acutis_escape$0(nullable$1[0])));
     } else {
-      buffer$1.push(acutis_escape$0("pass"));
+      buffer$1.push(Promise.resolve(acutis_escape$0("pass")));
     }
-    blocks$0[0] = buffer_to_promise$0(buffer$1);
+    blocks$0[0] = buffer_contents$0(buffer$1);
     let buffer$2 = [];
-    buffer$2.push(" Another nested block");
-    blocks$0[1] = buffer_to_promise$0(buffer$2);
+    buffer$2.push(Promise.resolve(" Another nested block"));
+    blocks$0[1] = buffer_contents$0(buffer$2);
     buffer$0.push(
       Promise.all(blocks$0).then(
         (arg$1) => {
@@ -1732,20 +1778,20 @@
           props$8.set("a", match_arg$13);
           props$8.set("b", match_arg$14);
           exit$7 = 0;
-          buffer$3.push(acutis_escape$0(props$8.get("a")));
-          buffer$3.push(" ");
-          buffer$3.push(acutis_escape$0(props$8.get("b")));
-          buffer$3.push("\n");
-          return (buffer_to_promise$0(buffer$3));
+          buffer$3.push(Promise.resolve(acutis_escape$0(props$8.get("a"))));
+          buffer$3.push(Promise.resolve(" "));
+          buffer$3.push(Promise.resolve(acutis_escape$0(props$8.get("b"))));
+          buffer$3.push(Promise.resolve("\n"));
+          return (buffer_contents$0(buffer$3));
         }
       )
     );
-    buffer$0.push("Component\n---------\n\n");
+    buffer$0.push(Promise.resolve("Component\n---------\n\n"));
     let blocks$1 =
       Array.from({length: 1}, (arg$1) => { return (Promise.resolve("")); });
     let buffer$3 = [];
-    buffer$3.push("Children prop");
-    blocks$1[0] = buffer_to_promise$0(buffer$3);
+    buffer$3.push(Promise.resolve("Children prop"));
+    blocks$1[0] = buffer_contents$0(buffer$3);
     buffer$0.push(
       Promise.all(blocks$1).then(
         (arg$1) => {
@@ -1761,19 +1807,21 @@
               )
             )
           );
-          return (buffer_to_promise$0(buffer$4));
+          return (buffer_contents$0(buffer$4));
         }
       )
     );
-    buffer$0.push("\n\n");
+    buffer$0.push(Promise.resolve("\n\n"));
     buffer$0.push(components$0.get("Another_function")(new Map([])));
     buffer$0.push(
-      "\n\
+      Promise.resolve(
+        "\n\
   \n\
   Complicated pattern matching\n\
   ----------------------------\n\
   \n\
   "
+      )
     );
     let arg_match$7 = [1, 0, 3];
     let props$8 = new Map(props$0);
@@ -1827,22 +1875,26 @@
       }
     }
     if (exit$7 === 0) {
-      buffer$0.push(" 0\n");
+      buffer$0.push(Promise.resolve(" 0\n"));
     } else {
       if (exit$7 === 1) {
-        buffer$0.push(" 1 ");
-        buffer$0.push(acutis_escape$0(props$8.get("x").toString()));
-        buffer$0.push("\n");
+        buffer$0.push(Promise.resolve(" 1 "));
+        buffer$0.push(
+          Promise.resolve(acutis_escape$0(props$8.get("x").toString()))
+        );
+        buffer$0.push(Promise.resolve("\n"));
       } else {
         if (exit$7 === 2) {
-          buffer$0.push(" 2 ");
-          buffer$0.push(acutis_escape$0(props$8.get("y").toString()));
-          buffer$0.push("\n");
+          buffer$0.push(Promise.resolve(" 2 "));
+          buffer$0.push(
+            Promise.resolve(acutis_escape$0(props$8.get("y").toString()))
+          );
+          buffer$0.push(Promise.resolve("\n"));
         } else {
           if (exit$7 === 3) {
-            buffer$0.push(" 3\n");
+            buffer$0.push(Promise.resolve(" 3\n"));
           } else {
-            buffer$0.push(" 4\n");
+            buffer$0.push(Promise.resolve(" 4\n"));
           }
         }
       }
@@ -1886,14 +1938,16 @@
       }
     }
     if (exit$8 === 0) {
-      buffer$0.push("\n");
+      buffer$0.push(Promise.resolve("\n"));
     } else {
       if (exit$8 === 1) {
-        buffer$0.push(" Pass\n");
+        buffer$0.push(Promise.resolve(" Pass\n"));
       } else {
-        buffer$0.push(" ");
-        buffer$0.push(acutis_escape$0(props$9.get("z").toString()));
-        buffer$0.push("\n");
+        buffer$0.push(Promise.resolve(" "));
+        buffer$0.push(
+          Promise.resolve(acutis_escape$0(props$9.get("z").toString()))
+        );
+        buffer$0.push(Promise.resolve("\n"));
       }
     }
     let arg_match$9 = [[[10, 20], 99], 40];
@@ -1935,32 +1989,40 @@
       }
     }
     if (exit$9 === 0) {
-      buffer$0.push("\n");
+      buffer$0.push(Promise.resolve("\n"));
     } else {
       if (exit$9 === 1) {
-        buffer$0.push(" Fail\n");
+        buffer$0.push(Promise.resolve(" Fail\n"));
       } else {
-        buffer$0.push(" ");
-        buffer$0.push(acutis_escape$0(props$10.get("z").toString()));
-        buffer$0.push("\n");
+        buffer$0.push(Promise.resolve(" "));
+        buffer$0.push(
+          Promise.resolve(acutis_escape$0(props$10.get("z").toString()))
+        );
+        buffer$0.push(Promise.resolve("\n"));
       }
     }
     buffer$0.push(
-      "String encoding\n\
+      Promise.resolve(
+        "String encoding\n\
   ---------------\n\
   \n\
   😇👨‍💻😇\n\
   \\\" \\ \\ \\\"\n\
   \n\
   "
+      )
+    );
+    buffer$0.push(
+      Promise.resolve(acutis_escape$0(props$0.get("unicode_string")))
     );
-    buffer$0.push(acutis_escape$0(props$0.get("unicode_string")));
     buffer$0.push(
-      "\n\
+      Promise.resolve(
+        "\n\
   \n\
   External JavaScript template component: stringify arbitrary data\n\
   \n\
   "
+      )
     );
     buffer$0.push(
       components$0.get("Stringify")(
@@ -1980,8 +2042,8 @@
         )
       )
     );
-    buffer$0.push("\n");
-    return (buffer_to_promise$0(buffer$0));
+    buffer$0.push(Promise.resolve("\n"));
+    return (buffer_contents$0(buffer$0));
   };
 
   $ cat > run.mjs << EOF
diff --git a/test/printjs/printjs_example.compiled.mjs b/test/printjs/printjs_example.compiled.mjs
index 1ebb29ad..26160156 100644
--- a/test/printjs/printjs_example.compiled.mjs
+++ b/test/printjs/printjs_example.compiled.mjs
@@ -18,7 +18,7 @@ let acutis_escape$0 =
     }
     return (result$0);
   };
-let buffer_to_promise$0 =
+let buffer_contents$0 =
   (arg$0) => {
     return (
       Promise.all(arg$0).then((arg$1) => { return (arg$1.join("")); })
@@ -360,9 +360,9 @@ The data supplied does not match this template's interface.\n\
     );
   }
   let buffer$0 = [];
-  buffer$0.push("<h1> Blog posts for ");
-  buffer$0.push(acutis_escape$0(props$0.get("siteTitle")));
-  buffer$0.push(" </h1>");
+  buffer$0.push(Promise.resolve("<h1> Blog posts for "));
+  buffer$0.push(Promise.resolve(acutis_escape$0(props$0.get("siteTitle"))));
+  buffer$0.push(Promise.resolve(" </h1>"));
   let index$0 = 0;
   let cell$0 = props$0.get("blogPosts");
   while (!(cell$0 === 0)) {
@@ -381,7 +381,11 @@ The data supplied does not match this template's interface.\n\
     props$1.set("name", match_arg$1);
     props$1.set("title", match_arg$5);
     exit$0 = 0;
-    buffer$0.push("\n  <article class=\"h-entry\">\n    <header>\n      ");
+    buffer$0.push(
+      Promise.resolve(
+        "\n  <article class=\"h-entry\">\n    <header>\n      "
+      )
+    );
     let arg_match$0 = [props$1.get("image")];
     let props$2 = new Map(props$1);
     let exit$1 = -1;
@@ -398,29 +402,39 @@ The data supplied does not match this template's interface.\n\
       exit$1 = 1;
     }
     if (!(exit$1 === 0)) {
-      buffer$0.push("<img src=\"");
-      buffer$0.push(acutis_escape$0(props$2.get("src")));
-      buffer$0.push("\" alt=\"");
-      buffer$0.push(acutis_escape$0(props$2.get("alt")));
-      buffer$0.push("\">\n      ");
+      buffer$0.push(Promise.resolve("<img src=\""));
+      buffer$0.push(Promise.resolve(acutis_escape$0(props$2.get("src"))));
+      buffer$0.push(Promise.resolve("\" alt=\""));
+      buffer$0.push(Promise.resolve(acutis_escape$0(props$2.get("alt"))));
+      buffer$0.push(Promise.resolve("\">\n      "));
     }
-    buffer$0.push("<h2 class=\"p-name\"> ");
-    buffer$0.push(acutis_escape$0(props$1.get("title")));
-    buffer$0.push(" </h2>\n      <span class=\"p-author\"> By ");
+    buffer$0.push(Promise.resolve("<h2 class=\"p-name\"> "));
+    buffer$0.push(Promise.resolve(acutis_escape$0(props$1.get("title"))));
+    buffer$0.push(
+      Promise.resolve(" </h2>\n      <span class=\"p-author\"> By ")
+    );
     let nullable$0 = props$1.get("name");
     if (!(nullable$0 === 0)) {
-      buffer$0.push(acutis_escape$0(nullable$0[0]));
+      buffer$0.push(Promise.resolve(acutis_escape$0(nullable$0[0])));
     } else {
-      buffer$0.push(acutis_escape$0("Anonymous"));
+      buffer$0.push(Promise.resolve(acutis_escape$0("Anonymous")));
     }
-    buffer$0.push(" </span>\n      <span class=\"dt-published\"> Posted on ");
-    buffer$0.push(acutis_escape$0(props$1.get("date")));
-    buffer$0.push(" </span>\n    </header>\n    <div class=\"e-content\"> ");
-    buffer$0.push(props$1.get("content"));
-    buffer$0.push(" </div>\n  </article>\n");
+    buffer$0.push(
+      Promise.resolve(
+        " </span>\n      <span class=\"dt-published\"> Posted on "
+      )
+    );
+    buffer$0.push(Promise.resolve(acutis_escape$0(props$1.get("date"))));
+    buffer$0.push(
+      Promise.resolve(
+        " </span>\n    </header>\n    <div class=\"e-content\"> "
+      )
+    );
+    buffer$0.push(Promise.resolve(props$1.get("content")));
+    buffer$0.push(Promise.resolve(" </div>\n  </article>\n"));
     index$0++;
     cell$0 = cell$0[1];
   }
-  buffer$0.push("\n");
-  return (buffer_to_promise$0(buffer$0));
+  buffer$0.push(Promise.resolve("\n"));
+  return (buffer_contents$0(buffer$0));
 };
\ No newline at end of file