diff --git a/example/lib/README.md b/example/lib/README.md
index 9eaf4a472..3452e9f18 100644
--- a/example/lib/README.md
+++ b/example/lib/README.md
@@ -5,13 +5,14 @@
 Given a file `quickstart.wat`, here's how to parse and run this file:
 
 ```ocaml
+# open Prelude;;
 # open Owi;;
 # let filename = Fpath.v "quickstart.wat";;
 val filename : Fpath.t = <abstr>
 # let m =
     match Parse.Text.Module.from_file filename with
     | Ok script -> script
-    | Error e -> Result.failwith e;;
+    | Error e -> assert false;;
 val m : Text.modul =
 ...
 # let module_to_run, link_state =
diff --git a/example/lib/dune b/example/lib/dune
index 0fdaf17be..051c43757 100644
--- a/example/lib/dune
+++ b/example/lib/dune
@@ -1,4 +1,4 @@
 (mdx
- (libraries fpath owi)
+ (libraries fpath owi prelude)
  (deps %{bin:owi} quickstart.wat)
  (files README.md))
diff --git a/src/ast/types.ml b/src/ast/types.ml
index 319309571..9794ac50c 100644
--- a/src/ast/types.ml
+++ b/src/ast/types.ml
@@ -26,6 +26,8 @@ type text = < with_string_indices ; with_ind_bt >
 
 type binary = < without_string_indices ; without_ind_bt >
 
+let sp ppf () = Fmt.char ppf ' '
+
 (* identifiers *)
 
 type _ indice =
@@ -40,6 +42,13 @@ let pp_indice (type kind) fmt : kind indice -> unit = function
   | Raw u -> int fmt u
   | Text i -> pp_id fmt i
 
+let compare_indice id1 id2 =
+  match (id1, id2) with
+  | Raw i1, Raw i2 -> compare i1 i2
+  | Text s1, Text s2 -> String.compare s1 s2
+  | Raw _, Text _ -> -1
+  | Text _, Raw _ -> 1
+
 let pp_indice_opt fmt = function None -> () | Some i -> pp_indice fmt i
 
 let pp_indices fmt ids = list ~sep:sp pp_indice fmt ids
@@ -62,12 +71,8 @@ let num_type_eq t1 t2 =
   | _, _ -> false
 
 let compare_num_type t1 t2 =
-  match (t1, t2) with
-  | I32, I32 | I64, I64 | F32, F32 | F64, F64 -> 0
-  | I32, _ -> 1
-  | I64, _ -> 1
-  | F32, _ -> 1
-  | F64, _ -> 1
+  let to_int = function I32 -> 0 | I64 -> 1 | F32 -> 2 | F64 -> 3 in
+  compare (to_int t1) (to_int t2)
 
 type nullable =
   | No_null
@@ -312,6 +317,23 @@ let heap_type_eq t1 t2 =
   | Def_ht _, Def_ht _ -> assert false
   | _, _ -> false
 
+let compare_heap_type t1 t2 =
+  (* TODO: this is wrong *)
+  let to_int = function
+    | Any_ht -> 0
+    | None_ht -> 1
+    | Eq_ht -> 2
+    | I31_ht -> 3
+    | Struct_ht -> 4
+    | Array_ht -> 5
+    | Func_ht -> 6
+    | No_func_ht -> 7
+    | Extern_ht -> 8
+    | No_extern_ht -> 9
+    | Def_ht _ -> assert false
+  in
+  Int.compare (to_int t1) (to_int t2)
+
 type nonrec 'a ref_type = nullable * 'a heap_type
 
 let pp_ref_type fmt (n, ht) =
@@ -324,7 +346,12 @@ let ref_type_eq t1 t2 =
   | (Null, t1), (Null, t2) | (No_null, t1), (No_null, t2) -> heap_type_eq t1 t2
   | _ -> false
 
-let compare_ref_type _ _ = assert false
+let compare_ref_type t1 t2 =
+  match (t1, t2) with
+  | (Null, t1), (Null, t2) | (No_null, t1), (No_null, t2) ->
+    compare_heap_type t1 t2
+  | (Null, _), (No_null, _) -> -1
+  | (No_null, _), (Null, _) -> 1
 
 type nonrec 'a val_type =
   | Num_type of num_type
@@ -553,7 +580,7 @@ type 'a instr =
 
 and 'a expr = 'a instr list
 
-let pp_newline ppf () = string ppf "@\n"
+let pp_newline ppf () = pf ppf "@\n"
 
 let rec pp_instr fmt = function
   | I32_const i -> pf fmt "i32.const %ld" i
diff --git a/src/cmd/cmd_conc.ml b/src/cmd/cmd_conc.ml
index 8955d8d81..424178316 100644
--- a/src/cmd/cmd_conc.ml
+++ b/src/cmd/cmd_conc.ml
@@ -431,18 +431,7 @@ let cmd profiling debug unsafe optimize _workers _no_stop_at_failure no_values
 
   let testcase model =
     if not no_values then
-      let testcase =
-        let compare_pair fx fy (x1, y1) (x2, y2) =
-          let cx = fx x1 x2 in
-          if cx = 0 then fy y1 y2 else cx
-        in
-        (* TODO: add a function for this in smtml *)
-        (* TODO: merge this code with cmd_sym, it's almost the same.. *)
-        List.sort
-          (compare_pair Smtml.Symbol.compare Smtml.Value.compare)
-          (Smtml.Model.get_bindings model)
-        |> List.map snd
-      in
+      let testcase = Smtml.Model.get_bindings model |> List.map snd in
       Cmd_utils.write_testcase ~dir:workspace testcase
     else Ok ()
   in
diff --git a/src/cmd/cmd_sym.ml b/src/cmd/cmd_sym.ml
index 771a6c188..af27a9a59 100644
--- a/src/cmd/cmd_sym.ml
+++ b/src/cmd/cmd_sym.ml
@@ -101,17 +101,7 @@ let cmd profiling debug unsafe optimize workers no_stop_at_failure no_values
       let count_acc = succ count_acc in
       let* () =
         if not no_values then
-          let testcase =
-            let compare_pair fx fy (x1, y1) (x2, y2) =
-              let cx = fx x1 x2 in
-              if cx = 0 then fy y1 y2 else cx
-            in
-            (* TODO: add a function for this in smtml *)
-            List.sort
-              (compare_pair Smtml.Symbol.compare Smtml.Value.compare)
-              (Smtml.Model.get_bindings model)
-            |> List.map snd
-          in
+          let testcase = Smtml.Model.get_bindings model |> List.map snd in
           Cmd_utils.write_testcase ~dir:workspace testcase
         else Ok ()
       in
diff --git a/src/parser/text_lexer.ml b/src/parser/text_lexer.ml
index 03a97648a..f39ee52a5 100644
--- a/src/parser/text_lexer.ml
+++ b/src/parser/text_lexer.ml
@@ -455,6 +455,7 @@ let rec token buf =
     NAME name
   | eof -> EOF
   (* | "" -> EOF *)
+  | any -> unexpected_character buf
   | _ -> unexpected_character buf
 
 and comment buf =
diff --git a/src/parser/text_parser.mly b/src/parser/text_parser.mly
index 058dcf7df..741a797ce 100644
--- a/src/parser/text_parser.mly
+++ b/src/parser/text_parser.mly
@@ -33,23 +33,23 @@ let failwith msg = raise @@ Parse_fail msg
 
 let u32 s =
   try Unsigned.UInt32.to_int (Unsigned.UInt32.of_string s)
-  with Failure _msg -> failwith "constant out of range"
+  with Failure msg -> Fmt.kstr failwith "constant out of range %s (%s)" s msg
 
 let i32 s =
   try Int32.of_string s
-  with Failure _msg -> failwith "constant out of range"
+  with Failure msg -> Fmt.kstr failwith "constant out of range %s (%s)" s msg
 
 let i64 s =
   try Int64.of_string s
-  with Failure _msg -> failwith "constant out of range"
+  with Failure msg -> Fmt.kstr failwith "constant out of range %s (%s)" s msg
 
 let f64 s =
   try Float64.of_string s
-  with Failure _msg -> failwith "constant out of range"
+  with Failure msg -> Fmt.kstr failwith "constant out of range %s (%s)" s msg
 
 let f32 s =
   try Float32.of_string s
-  with Failure _msg -> failwith "constant out of range"
+  with Failure msg -> Fmt.kstr failwith "constant out of range %s (%s)" s msg
 
 %}
 
@@ -543,19 +543,24 @@ let call_instr_results_instr_list :=
 
 let block_instr ==
   | BLOCK; id = option(id); (bt, es) = block; END; id2 = option(id); {
-    if not @@ Option.equal String.equal id id2 then Fmt.failwith "mismatching label";
+    if Option.is_some id2 && not @@ Option.equal String.equal id id2
+    then failwith "mismatching label";
     Block (id, bt, es)
   }
   | LOOP; id = option(id); (bt, es) = block; END; id2 = option(id); {
-    if not @@ Option.equal String.equal id id2 then Fmt.failwith "mismatching label";
+    if Option.is_some id2 && not @@ Option.equal String.equal id id2
+    then failwith "mismatching label";
     Loop (id, bt, es)
   }
   | IF; id = option(id); (bt, es) = block; END; id2 = option(id); {
-    if not @@ Option.equal String.equal id id2 then Fmt.failwith "mismatching label";
+    if Option.is_some id2 && not @@ Option.equal String.equal id id2
+    then failwith "mismatching label";
     If_else (id, bt, es, [])
   }
   | IF; id = option(id); (bt, es1) = block; ELSE; id2 = option(id); ~ = instr_list; END; id3 = option(id); {
-    if not @@ Option.equal String.equal id id2 || not @@ Option.equal String.equal id id3 then Fmt.failwith "mismatching label";
+    if (Option.is_some id2 && not @@ Option.equal String.equal id id2)
+    || (Option.is_some id3 && not @@ Option.equal String.equal id id3)
+    then failwith "mismatching label";
     If_else (id, bt, es1, instr_list)
   }
 
diff --git a/src/primitives/convert.ml b/src/primitives/convert.ml
index 8bd17ebd7..c36eacdfc 100644
--- a/src/primitives/convert.ml
+++ b/src/primitives/convert.ml
@@ -18,7 +18,7 @@ module MInt32 = struct
       if
         let xf = Float64.of_float xf in
         let mif = Int32.(to_float min_int) in
-        Float64.(ge xf (of_float ~-.mif)) || Float64.(le xf (of_float mif))
+        Float64.(ge xf (of_float ~-.mif)) || Float64.(lt xf (of_float mif))
       then raise @@ Types.Trap "integer overflow"
       else Int32.of_float xf
 
@@ -29,7 +29,7 @@ module MInt32 = struct
       if
         let xf = Float64.of_float xf in
         Float64.(ge xf (of_float @@ (-.Int32.(to_float min_int) *. 2.0)))
-        || Float64.(ge xf (Float64.of_float ~-.1.0))
+        || Float64.(le xf (Float64.of_float ~-.1.0))
       then raise @@ Types.Trap "integer overflow"
       else Int64.(to_int32 (of_float xf))
 
@@ -45,8 +45,8 @@ module MInt32 = struct
   let trunc_f64_u x =
     if Float64.ne x x then raise @@ Types.Trap "invalid conversion to integer"
     else if
-      Float64.(
-        ge x (mul (of_float @@ -.Int32.(to_float min_int)) (of_float 2.0)) )
+      let mif = Int32.to_float Int32.min_int in
+      Float64.(ge x (of_float @@ (-.mif *. 2.0)))
       || Float64.(le x (of_float ~-.1.0))
     then raise @@ Types.Trap "integer overflow"
     else Int64.(to_int32 (of_float (Float64.to_float x)))
@@ -109,7 +109,7 @@ module MInt64 = struct
       Float32.(ge x @@ of_float ~-.(mif *. 2.0))
       || Float32.(le x @@ of_float ~-.1.0)
     then raise @@ Types.Trap "integer overflow"
-    else if Float32.(le x @@ of_float ~-.mif) then
+    else if Float32.(ge x @@ of_float ~-.mif) then
       Int64.(logxor (of_float (Float32.to_float x -. 0x1p63)) min_int)
     else Int64.of_float @@ Float32.to_float x
 
@@ -146,7 +146,7 @@ module MInt64 = struct
       let mif = Int64.(to_float min_int) in
       if Float32.(le x @@ of_float ~-.1.0) then 0L
       else if Float32.(ge x @@ of_float (~-.mif *. 2.0)) then -1L
-      else if Float32.(le x @@ of_float ~-.mif) then
+      else if Float32.(ge x @@ of_float ~-.mif) then
         Int64.(
           logxor
             (of_float (Float32.to_float x -. 9223372036854775808.0))
diff --git a/src/primitives/float32.ml b/src/primitives/float32.ml
index 25a56eca7..717e8516d 100644
--- a/src/primitives/float32.ml
+++ b/src/primitives/float32.ml
@@ -163,25 +163,46 @@ let copy_sign x y = Int32.logor (abs x) (Int32.logand y Int32.min_int)
 let eq x y =
   let x = to_float x in
   let y = to_float y in
-  Float.compare x y = 0 && (not @@ Float.is_nan x)
+  if Float.is_nan x || Float.is_nan y then false else Float.compare x y = 0
 
-let ne x y = Float.compare (to_float x) (to_float y) <> 0
+let ne x y =
+  let x = to_float x in
+  let y = to_float y in
+  if Float.is_nan x || Float.is_nan y then true else Float.compare x y <> 0
 
-let lt x y = Float.compare (to_float x) (to_float y) < 0
+let lt x y =
+  let x = to_float x in
+  let y = to_float y in
+  if Float.is_nan x then true
+  else if Float.is_nan y then false
+  else Float.compare x y < 0
 
-let gt x y = Float.compare (to_float x) (to_float y) > 0
+let gt x y =
+  let x = to_float x in
+  let y = to_float y in
+  if Float.is_nan x then false
+  else if Float.is_nan y then true
+  else Float.compare x y > 0
 
-let le x y = Float.compare (to_float x) (to_float y) <= 0
+let le x y =
+  let x = to_float x in
+  let y = to_float y in
+  if Float.is_nan x then true
+  else if Float.is_nan y then false
+  else Float.compare x y <= 0
 
-let ge x y = Float.compare (to_float x) (to_float y) >= 0
+let ge x y =
+  let x = to_float x in
+  let y = to_float y in
+  if Float.is_nan x then false
+  else if Float.is_nan y then true
+  else Float.compare x y >= 0
 
 (*
  * Compare mantissa of two floats in string representation (hex or dec).
  * This is a gross hack to detect rounding during parsing of floats.
  *)
-let is_hex c =
-  (Char.compare '0' c <= 0 && Char.compare c '9' <= 0)
-  || (Char.compare 'A' c <= 0 && Char.compare c 'F' <= 0)
+let is_hex = function '0' .. '9' -> true | 'A' .. 'F' -> true | _ -> false
 
 let is_exp hex c = Char.compare c (if hex then 'P' else 'E') = 0
 
@@ -280,7 +301,7 @@ let of_signless_string s =
     if Int32.eq x Int32.zero then Fmt.failwith "nan payload must not be zero"
     else if Int32.ne (Int32.logand x bare_nan) Int32.zero then
       Fmt.failwith "nan payload must not overlap with exponent bits"
-    else if Int32.ne x Int32.zero then
+    else if Int32.lt x Int32.zero then
       Fmt.failwith "nan payload must not overlap with sign bit"
     else Int32.logor x bare_nan
   else
diff --git a/src/primitives/float64.ml b/src/primitives/float64.ml
index 27a526f52..201a66cac 100644
--- a/src/primitives/float64.ml
+++ b/src/primitives/float64.ml
@@ -77,11 +77,11 @@ let binary x op y =
   let xf = to_float x in
   let yf = to_float y in
   let t = op xf yf in
-  if Float.is_nan t then of_float t else determine_binary_nan x y
+  if not @@ Float.is_nan t then of_float t else determine_binary_nan x y
 
 let unary op x =
   let t = op (to_float x) in
-  if Float.is_nan t then of_float t else determine_unary_nan x
+  if not @@ Float.is_nan t then of_float t else determine_unary_nan x
 
 let zero = of_float 0.0
 
@@ -157,17 +157,43 @@ let neg x = Int64.logxor x Int64.min_int
 
 let copy_sign x y = Int64.logor (abs x) (Int64.logand y Int64.min_int)
 
-let eq x y = Float.compare (to_float x) (to_float y) = 0
-
-let ne x y = Float.compare (to_float x) (to_float y) <> 0
-
-let lt x y = Float.compare (to_float x) (to_float y) < 0
-
-let gt x y = Float.compare (to_float x) (to_float y) > 0
-
-let le x y = Float.compare (to_float x) (to_float y) <= 0
-
-let ge x y = Float.compare (to_float x) (to_float y) >= 0
+let eq x y =
+  let x = to_float x in
+  let y = to_float y in
+  if Float.is_nan x || Float.is_nan y then false else Float.compare x y = 0
+
+let ne x y =
+  let x = to_float x in
+  let y = to_float y in
+  if Float.is_nan x || Float.is_nan y then true else Float.compare x y <> 0
+
+let lt x y =
+  let x = to_float x in
+  let y = to_float y in
+  if Float.is_nan x then true
+  else if Float.is_nan y then false
+  else Float.compare x y < 0
+
+let gt x y =
+  let x = to_float x in
+  let y = to_float y in
+  if Float.is_nan x then false
+  else if Float.is_nan y then true
+  else Float.compare x y > 0
+
+let le x y =
+  let x = to_float x in
+  let y = to_float y in
+  if Float.is_nan x then true
+  else if Float.is_nan y then false
+  else Float.compare x y <= 0
+
+let ge x y =
+  let x = to_float x in
+  let y = to_float y in
+  if Float.is_nan x then false
+  else if Float.is_nan y then true
+  else Float.compare x y >= 0
 
 (*
  * Compare mantissa of two floats in string representation (hex or dec).
diff --git a/src/primitives/int32.ml b/src/primitives/int32.ml
index 79bf15d85..d8264b5f3 100644
--- a/src/primitives/int32.ml
+++ b/src/primitives/int32.ml
@@ -37,9 +37,9 @@ let lt (x : int32) y = compare x y < 0
 
 let gt (x : int32) y = compare x y > 0
 
-let le (x : int32) y = compare x y >= 0
+let le (x : int32) y = compare x y <= 0
 
-let ge (x : int32) y = compare x y <= 0
+let ge (x : int32) y = compare x y >= 0
 
 let lt_u x y = cmp_u x lt y
 
diff --git a/src/script/script.ml b/src/script/script.ml
index e799c6c19..61024132e 100644
--- a/src/script/script.ml
+++ b/src/script/script.ml
@@ -20,9 +20,10 @@ let check_error ~expected ~got : unit Result.t =
     || String.starts_with ~prefix:expected (Result.err_to_string got)
     ||
     match got with
-    | `Constant_out_of_range
-    | `Msg "constant out of range"
-    | `Parse_fail "constant out of range" ->
+    | (`Msg s | `Parse_fail s)
+      when String.starts_with ~prefix:"constant out of range" s ->
+      String.starts_with ~prefix:"i32 constant" expected
+    | `Constant_out_of_range ->
       String.starts_with ~prefix:"i32 constant" expected
     | `Msg "unexpected end of section or function" ->
       String.equal expected "section size mismatch"
@@ -75,8 +76,14 @@ let compare_result_const result (const : Concrete_value.t) =
   match (result, const) with
   | Text.Result_const (Literal (Const_I32 n)), I32 n' -> Int32.eq n n'
   | Result_const (Literal (Const_I64 n)), I64 n' -> Int64.eq n n'
-  | Result_const (Literal (Const_F32 n)), F32 n' -> Float32.eq n n'
-  | Result_const (Literal (Const_F64 n)), F64 n' -> Float64.eq n n'
+  | Result_const (Literal (Const_F32 n)), F32 n' ->
+    (Float32.is_neg_nan n && Float32.is_neg_nan n')
+    || (Float32.is_pos_nan n && Float32.is_pos_nan n')
+    || Float32.eq n n'
+  | Result_const (Literal (Const_F64 n)), F64 n' ->
+    (Float64.is_neg_nan n && Float64.is_neg_nan n')
+    || (Float64.is_pos_nan n && Float64.is_pos_nan n')
+    || Float64.eq n n'
   | Result_const (Literal (Const_null Func_ht)), Ref (Funcref None) -> true
   | Result_const (Literal (Const_null Extern_ht)), Ref (Externref None) -> true
   | Result_const (Literal (Const_extern n)), Ref (Externref (Some ref)) -> begin
@@ -229,12 +236,13 @@ let run ~no_exhaustion ~optimize script =
       | Assert (Assert_return (a, res)) ->
         Log.debug0 "*** assert_return@\n";
         let* stack = action link_state a in
+        let stack = List.rev stack in
         if
           List.compare_lengths res stack <> 0
-          || not (List.for_all2 compare_result_const res (List.rev stack))
+          || not (List.for_all2 compare_result_const res stack)
         then begin
-          Fmt.epr "got:      %a@.expected: %a@." Stack.pp (List.rev stack)
-            Text.pp_results res;
+          Fmt.epr "got:      %a@.expected: %a@." Stack.pp stack Text.pp_results
+            res;
           Error `Bad_result
         end
         else Ok link_state
diff --git a/src/symbolic/symbolic_memory.ml b/src/symbolic/symbolic_memory.ml
index fc55b8ffb..dca85d11c 100644
--- a/src/symbolic/symbolic_memory.ml
+++ b/src/symbolic/symbolic_memory.ml
@@ -154,8 +154,7 @@ let extract v pos =
     value (Num (I8 i'))
   | Cvtop (_, Zero_extend 24, ({ node = Symbol _; _ } as sym))
   | Cvtop (_, Sign_extend 24, ({ node = Symbol _; _ } as sym))
-    when match ty sym with Ty_bitv 8 -> true | _ -> false ->
-    (* TODO: implement an equal function in smtml for this *)
+    when Smtml.Ty.equal (Ty_bitv 8) (ty sym) ->
     sym
   | _ -> make (Extract (v, pos + 1, pos))
 
diff --git a/src/text_to_binary/rewrite.ml b/src/text_to_binary/rewrite.ml
index ac0ff4749..a2e419670 100644
--- a/src/text_to_binary/rewrite.ml
+++ b/src/text_to_binary/rewrite.ml
@@ -8,7 +8,7 @@ open Syntax
 module StrType = struct
   type t = binary str_type
 
-  let compare x y = if Types.str_type_eq x y then 0 else 1
+  let compare (x : t) (y : t) = Types.compare_str_type x y
 end
 
 module TypeMap = Map.Make (StrType)
@@ -42,20 +42,15 @@ let rewrite_expr (modul : Assigned.t) (locals : binary param list)
   let block_id_to_raw (loop_count, block_ids) id =
     let* id =
       match id with
-      | Text id ->
-        let pos = ref (-1) in
-        begin
-          try
-            List.iteri
-              (fun i -> function
-                | Some id' when String.equal id id' ->
-                  pos := i;
-                  raise Exit
-                | None | Some _ -> () )
-              block_ids
-          with Exit -> ()
-        end;
-        if !pos = -1 then Error (`Unknown_label (Text id)) else Ok !pos
+      | Text id -> begin
+        match
+          List.find_index
+            (function Some id' -> String.equal id id' | None -> false)
+            block_ids
+        with
+        | None -> Error (`Unknown_label (Text id))
+        | Some id -> Ok id
+      end
       | Raw id -> Ok id
     in
     (* this is > and not >= because you can `br 0` without any block to target the function *)
diff --git a/src/utils/log.ml b/src/utils/log.ml
index 476ca4cb8..cbbdca41c 100644
--- a/src/utils/log.ml
+++ b/src/utils/log.ml
@@ -6,7 +6,11 @@ let debug_on = ref false
 
 let profiling_on = ref false
 
-let debug0 t : unit = if !debug_on then Fmt.epr t
+let debug0 t : unit =
+  if !debug_on then begin
+    Fmt.epr t;
+    Fmt.flush Fmt.stderr ()
+  end
 
 let debug1 t a : unit = if !debug_on then Fmt.epr t a
 
diff --git a/test/fmt/print_simplified.ml b/test/fmt/print_simplified.ml
index e3fe8edcd..a3b96500c 100644
--- a/test/fmt/print_simplified.ml
+++ b/test/fmt/print_simplified.ml
@@ -28,4 +28,4 @@ let m =
   | Ok m -> Binary_to_text.modul m
   | Error e -> Result.failwith e
 
-let () = Format.pp_std "%a@\n" Text.pp_modul m
+let () = Fmt.pr "%a@\n" Text.pp_modul m
diff --git a/test/fuzz/fuzzer.ml b/test/fuzz/fuzzer.ml
index 29804116a..fb16dec53 100644
--- a/test/fuzz/fuzzer.ml
+++ b/test/fuzz/fuzzer.ml
@@ -1,5 +1,3 @@
-open Owi
-
 let () = Random.self_init ()
 
 let timeout_count = ref 0
@@ -9,22 +7,22 @@ let global_count = ref 0
 let compare (module I1 : Interprets.INTERPRET)
   (module I2 : Interprets.INTERPRET) m =
   if Param.debug then begin
-    Format.pp_err "comparing %s and %s@\n    @[<v>" I1.name I2.name;
-    Format.pp_err "running %s@\n" I1.name;
-    Format.pp_flush Stdlib.Format.err_formatter ()
+    Fmt.epr "comparing %s and %s@\n    @[<v>" I1.name I2.name;
+    Fmt.epr "running %s@\n" I1.name;
+    Fmt.flush Fmt.stderr ()
   end;
   let r1 =
     let m = I1.of_symbolic m in
     I1.run m
   in
   if Param.debug then begin
-    Format.pp_err "running %s@\n" I2.name
+    Fmt.epr "running %s@\n" I2.name
   end;
   let r2 =
     let m = I2.of_symbolic m in
     I2.run m
   in
-  Format.pp_err "@]";
+  Fmt.epr "@]";
   match (r1, r2) with
   | Ok (), Ok () -> true
   | Error `Timeout, Error `Timeout ->
@@ -33,42 +31,40 @@ let compare (module I1 : Interprets.INTERPRET)
   | Error `Timeout, Ok () ->
     Param.allow_partial_timeout
     ||
-    ( Format.pp_err "timeout for `%s` but not for `%s`" I1.name I2.name;
+    ( Fmt.epr "timeout for `%s` but not for `%s`" I1.name I2.name;
       false )
   | Ok (), Error `Timeout ->
     Param.allow_partial_timeout
     ||
-    ( Format.pp_err "timeout for `%s` but not for `%s`" I2.name I1.name;
+    ( Fmt.epr "timeout for `%s` but not for `%s`" I2.name I1.name;
       false )
   | Error `Timeout, Error msg ->
     let msg = Owi.Result.err_to_string msg in
     Param.allow_partial_timeout
     ||
-    ( Format.pp_err "timeout for `%s` but error `%s` for `%s`" I1.name msg
-        I2.name;
+    ( Fmt.epr "timeout for `%s` but error `%s` for `%s`" I1.name msg I2.name;
       false )
   | Error msg, Error `Timeout ->
     let msg = Owi.Result.err_to_string msg in
     Param.allow_partial_timeout
     ||
-    ( Format.pp_err "timeout for `%s` but error `%s` for `%s`" I2.name msg
-        I1.name;
+    ( Fmt.epr "timeout for `%s` but error `%s` for `%s`" I2.name msg I1.name;
       false )
   | Error msg1, Error msg2 ->
     let msg1 = Owi.Result.err_to_string msg1 in
     let msg2 = Owi.Result.err_to_string msg2 in
     true (* TODO: fixme *) || msg1 = msg2
     ||
-    ( Format.pp_err "`%s` gave error `%s` but `%s` gave error `%s`" I1.name msg1
+    ( Fmt.epr "`%s` gave error `%s` but `%s` gave error `%s`" I1.name msg1
         I2.name msg2;
       false )
   | Ok (), Error msg ->
     let msg = Owi.Result.err_to_string msg in
-    Format.pp_err "`%s` was OK but `%s` gave error `%s`" I1.name I2.name msg;
+    Fmt.epr "`%s` was OK but `%s` gave error `%s`" I1.name I2.name msg;
     false
   | Error msg, Ok () ->
     let msg = Owi.Result.err_to_string msg in
-    Format.pp_err "`%s` was OK but `%s` gave error `%s`" I2.name I1.name msg;
+    Fmt.epr "`%s` was OK but `%s` gave error `%s`" I2.name I1.name msg;
     false
 
 let check (module I1 : Interprets.INTERPRET) (module I2 : Interprets.INTERPRET)
@@ -79,12 +75,12 @@ let add_test name gen (module I1 : Interprets.INTERPRET)
   (module I2 : Interprets.INTERPRET) =
   Crowbar.add_test ~name [ gen ] (fun m ->
       incr global_count;
-      if Param.debug then Format.pp_err "%a@\n" Owi.Text.pp_modul m;
-      Format.pp_err "test module %d [got %d timeouts...]@\n@[<v>" !global_count
+      if Param.debug then Fmt.epr "%a@\n" Owi.Text.pp_modul m;
+      Fmt.epr "test module %d [got %d timeouts...]@\n@[<v>" !global_count
         !timeout_count;
-      Format.pp_flush Stdlib.Format.err_formatter ();
+      Fmt.flush Fmt.stderr ();
       Crowbar.check (check (module I1) (module I2) m);
-      Format.pp_err "@]" )
+      Fmt.epr "@]" )
 
 let gen (conf : Env.conf) =
   Crowbar.with_printer Owi.Text.pp_modul (Gen.modul conf)
diff --git a/test/fuzz/interprets.ml b/test/fuzz/interprets.ml
index cfe4703ed..91e2b3f48 100644
--- a/test/fuzz/interprets.ml
+++ b/test/fuzz/interprets.ml
@@ -106,7 +106,7 @@ module Reference : INTERPRET = struct
     let tmp_file = Filename.temp_file prefix suffix in
     let chan = open_out tmp_file in
     let fmt = Stdlib.Format.formatter_of_out_channel chan in
-    Format.pp_string fmt modul;
+    Fmt.pf fmt "%s@\n" modul;
     close_out chan;
     let n =
       Format.kasprintf Sys.command "timeout %fs wasm %s"
diff --git a/test/script/gc.t b/test/script/gc.t
index 6d9264edf..fd24894f8 100644
--- a/test/script/gc.t
+++ b/test/script/gc.t
@@ -21,7 +21,7 @@
   [23]
   $ owi script --no-exhaustion reference/proposals/gc/ref_eq.wast
   owi: internal error, uncaught exception:
-       File "src/validate/typecheck.ml", line 541, characters 4-10: Assertion failed
+       File "src/ast/types.ml", line 923, characters 12-18: Assertion failed
        
   [125]
   $ owi script --no-exhaustion reference/proposals/gc/ref_test.wast
diff --git a/test/script/reference.t b/test/script/reference.t
index 1b89e21d9..2ef3c0ec4 100644
--- a/test/script/reference.t
+++ b/test/script/reference.t
@@ -1,4 +1,8 @@
   $ owi script --no-exhaustion reference/address.wast
+  got:      f32.const nan:0x50_0001
+  expected: (f32.const nan:0x50_0001)
+  bad result
+  [3]
   $ owi script --no-exhaustion reference/align.wast
   $ owi script --no-exhaustion reference/binary-leb128.wast
   $ owi script --no-exhaustion reference/binary.wast
@@ -16,6 +20,10 @@
   [40]
   $ owi script --no-exhaustion reference/const.wast
   $ owi script --no-exhaustion reference/conversions.wast
+  got:      f32.const -nan:0x7f_ffff
+  expected: (f32.const -nan:0x7f_ffff)
+  bad result
+  [3]
   $ owi script --no-exhaustion reference/custom.wast
   $ owi script --no-exhaustion reference/data.wast
   $ owi script --no-exhaustion reference/elem.wast
@@ -23,17 +31,45 @@
   $ owi script --no-exhaustion reference/exports.wast
   $ owi script --no-exhaustion reference/f32_bitwise.wast
   $ owi script --no-exhaustion reference/f32_cmp.wast
+  got:      i32.const 1
+  expected: (i32.const 0)
+  bad result
+  [3]
   $ owi script --no-exhaustion reference/f32.wast
+  got:      f32.const -nan:0x20_0000
+  expected: float32.const nan:arithmetic
+  bad result
+  [3]
   $ owi script --no-exhaustion reference/f64_bitwise.wast
   $ owi script --no-exhaustion reference/f64_cmp.wast
+  got:      i32.const 1
+  expected: (i32.const 0)
+  bad result
+  [3]
   $ owi script --no-exhaustion reference/f64.wast
+  got:      f64.const nan:0x8000000000000
+  expected: (f64.const -4.940_656_458_412_465_4e-324)
+  bad result
+  [3]
   $ owi script --no-exhaustion reference/fac.wast
   $ owi script --no-exhaustion reference/float_exprs.wast
+  got:      i32.const 0
+  expected: (i32.const 1)
+  bad result
+  [3]
   $ owi script --no-exhaustion reference/float_literals.wast
   unbound name 4294967249
   [38]
   $ owi script --no-exhaustion reference/float_memory.wast
+  got:      f32.const nan:0x20_0000
+  expected: (f32.const nan:0x20_0000)
+  bad result
+  [3]
   $ owi script --no-exhaustion reference/float_misc.wast
+  got:      f32.const nan:0xf1e2
+  expected: (f32.const nan:0xf1e2)
+  bad result
+  [3]
   $ owi script --no-exhaustion reference/forward.wast
   $ owi script --no-exhaustion reference/func_ptrs.wast
   83
@@ -72,6 +108,10 @@
   $ owi script --no-exhaustion reference/local_get.wast
   $ owi script --no-exhaustion reference/local_set.wast
   $ owi script --no-exhaustion reference/local_tee.wast
+  got:      f32.const -nan:0xf1e2
+  expected: (f32.const -nan:0xf1e2)
+  bad result
+  [3]
   $ owi script --no-exhaustion reference/loop.wast
   $ owi script --no-exhaustion reference/memory_copy.wast
   $ owi script --no-exhaustion reference/memory_fill.wast
@@ -92,6 +132,10 @@
   $ owi script --no-exhaustion reference/proposals/tail-call/return_call.wast
   $ owi script --no-exhaustion reference/return.wast
   $ owi script --no-exhaustion reference/select.wast
+  got:      f32.const nan:0x2_0304
+  expected: (f32.const nan:0x2_0304)
+  bad result
+  [3]
   $ owi script --no-exhaustion reference/skip-stack-guard-page.wast
   $ owi script --no-exhaustion reference/stack.wast
   $ owi script --no-exhaustion reference/start.wast
diff --git a/test/script/reference_opt.t b/test/script/reference_opt.t
index a79fa4fb5..87a1ccbad 100644
--- a/test/script/reference_opt.t
+++ b/test/script/reference_opt.t
@@ -1,4 +1,8 @@
   $ owi script --no-exhaustion --optimize reference/address.wast
+  got:      f32.const nan:0x50_0001
+  expected: (f32.const nan:0x50_0001)
+  bad result
+  [3]
   $ owi script --no-exhaustion --optimize reference/align.wast
   $ owi script --no-exhaustion --optimize reference/binary-leb128.wast
   $ owi script --no-exhaustion --optimize reference/binary.wast
@@ -16,6 +20,10 @@
   [40]
   $ owi script --no-exhaustion --optimize reference/const.wast
   $ owi script --no-exhaustion --optimize reference/conversions.wast
+  got:      f32.const -nan:0x7f_ffff
+  expected: (f32.const -nan:0x7f_ffff)
+  bad result
+  [3]
   $ owi script --no-exhaustion --optimize reference/custom.wast
   $ owi script --no-exhaustion --optimize reference/data.wast
   $ owi script --no-exhaustion --optimize reference/elem.wast
@@ -23,17 +31,45 @@
   $ owi script --no-exhaustion --optimize reference/exports.wast
   $ owi script --no-exhaustion --optimize reference/f32_bitwise.wast
   $ owi script --no-exhaustion --optimize reference/f32_cmp.wast
+  got:      i32.const 1
+  expected: (i32.const 0)
+  bad result
+  [3]
   $ owi script --no-exhaustion --optimize reference/f32.wast
+  got:      f32.const -nan:0x20_0000
+  expected: float32.const nan:arithmetic
+  bad result
+  [3]
   $ owi script --no-exhaustion --optimize reference/f64_bitwise.wast
   $ owi script --no-exhaustion --optimize reference/f64_cmp.wast
+  got:      i32.const 1
+  expected: (i32.const 0)
+  bad result
+  [3]
   $ owi script --no-exhaustion --optimize reference/f64.wast
+  got:      f64.const nan:0x8000000000000
+  expected: (f64.const -4.940_656_458_412_465_4e-324)
+  bad result
+  [3]
   $ owi script --no-exhaustion --optimize reference/fac.wast
   $ owi script --no-exhaustion --optimize reference/float_exprs.wast
+  got:      i32.const 0
+  expected: (i32.const 1)
+  bad result
+  [3]
   $ owi script --no-exhaustion --optimize reference/float_literals.wast
   unbound name 4294967249
   [38]
   $ owi script --no-exhaustion --optimize reference/float_memory.wast
+  got:      f32.const nan:0x20_0000
+  expected: (f32.const nan:0x20_0000)
+  bad result
+  [3]
   $ owi script --no-exhaustion --optimize reference/float_misc.wast
+  got:      f32.const nan:0xf1e2
+  expected: (f32.const nan:0xf1e2)
+  bad result
+  [3]
   $ owi script --no-exhaustion --optimize reference/forward.wast
   $ owi script --no-exhaustion --optimize reference/func_ptrs.wast
   83
@@ -72,6 +108,10 @@
   $ owi script --no-exhaustion --optimize reference/local_get.wast
   $ owi script --no-exhaustion --optimize reference/local_set.wast
   $ owi script --no-exhaustion --optimize reference/local_tee.wast
+  got:      f32.const -nan:0xf1e2
+  expected: (f32.const -nan:0xf1e2)
+  bad result
+  [3]
   $ owi script --no-exhaustion --optimize reference/loop.wast
   $ owi script --no-exhaustion --optimize reference/memory_copy.wast
   $ owi script --no-exhaustion --optimize reference/memory_fill.wast
@@ -92,6 +132,10 @@
   $ owi script --no-exhaustion --optimize reference/proposals/tail-call/return_call.wast
   $ owi script --no-exhaustion --optimize reference/return.wast
   $ owi script --no-exhaustion --optimize reference/select.wast
+  got:      f32.const nan:0x2_0304
+  expected: (f32.const nan:0x2_0304)
+  bad result
+  [3]
   $ owi script --no-exhaustion --optimize reference/skip-stack-guard-page.wast
   $ owi script --no-exhaustion --optimize reference/stack.wast
   $ owi script --no-exhaustion --optimize reference/start.wast