diff --git a/examples/.gitignore b/examples/.gitignore
new file mode 100644
index 00000000..698fc63c
--- /dev/null
+++ b/examples/.gitignore
@@ -0,0 +1,5 @@
+filtering
+filtering_pos
+*.cmi
+*.cmx
+*.o
diff --git a/examples/filtering.json b/examples/filtering.json
index a576b979..311db8f7 100644
--- a/examples/filtering.json
+++ b/examples/filtering.json
@@ -1,4 +1,4 @@
-{                                     
+{
   "id": "398eb027",
   "name": "John Doe",
   "pages": [
diff --git a/examples/filtering_broken.json b/examples/filtering_broken.json
new file mode 100644
index 00000000..a4d296d0
--- /dev/null
+++ b/examples/filtering_broken.json
@@ -0,0 +1,22 @@
+{
+  "id": "398eb027",
+  "name": "John Doe",
+  "pages": [
+    {
+      "id": 1,
+      "title": "The Art of Flipping Coins",
+      "url": "http://example.com/398eb027/1"
+    },
+    { "id": 2, "deleted": true },
+    {
+      "id": 3,
+        "title": { "foo": "an example of broken value" },
+      "url": "http://example.com/398eb027/3"
+    },
+    {
+      "id": 4,
+      "title": "Flying Bananas",
+      "url": "http://example.com/398eb027/4"
+    }
+  ]
+}
diff --git a/examples/filtering_pos.ml b/examples/filtering_pos.ml
new file mode 100644
index 00000000..c59df458
--- /dev/null
+++ b/examples/filtering_pos.ml
@@ -0,0 +1,51 @@
+open Yojson.SafePos.Util
+open Format
+
+let pp_position ppf pos =
+  let open Yojson in
+  let fnamestr =
+    match pos.file_name with
+    | None -> ""
+    | Some(x) -> " in '" ^ x ^ "'"
+  in
+  let lnum1 = pos.start_line in
+  let lnum2 = pos.end_line in
+  if lnum1 = lnum2 then
+    fprintf ppf "line %d, column %d-%d%s"
+      lnum1 pos.start_column pos.end_column fnamestr
+  else
+    fprintf ppf "line %d column %d to line %d, column %d"
+      lnum1 pos.start_column lnum2 pos.end_column
+
+let print_with_pos pp ((pos, _) as a) =
+  printf "%a (%a)@," pp a pp_position pos
+
+let pp_object ppf _ =
+  fprintf ppf "<obj>"
+
+let extract_titles json =
+  let objs =
+    [json]
+      |> filter_member "pages"
+      |> flatten
+  in
+  List.iter (print_with_pos pp_object) objs;
+  objs
+    |> filter_member "title"
+    |> List.map to_string
+
+let main () =
+  printf "@[<v0>";
+  begin
+    try
+      let json = Yojson.SafePos.from_channel stdin in
+      List.iter (printf "%s@,") (extract_titles json);
+    with
+    | Yojson.SafePos.Util.Type_error(msg, json) ->
+        printf "! [ERROR] %s:@," msg;
+        printf "! ";
+        print_with_pos Yojson.SafePos.pretty_print json
+  end;
+  printf "@]"
+
+let () = main ()
diff --git a/examples/run-examples.sh b/examples/run-examples.sh
index 4c72ed6f..2123cec4 100755
--- a/examples/run-examples.sh
+++ b/examples/run-examples.sh
@@ -3,3 +3,10 @@
 echo "----- Example 1: filtering -----"
 ocamlfind ocamlopt -o filtering filtering.ml -package yojson -linkpkg
 ./filtering < filtering.json
+
+echo "----- Example 2: filtering_pos -----"
+ocamlfind ocamlopt -o filtering_pos filtering_pos.ml -package yojson -linkpkg
+echo "..... Example 2.1 ....."
+./filtering_pos < filtering.json
+echo "..... Example 2.2 ....."
+./filtering_pos < filtering_broken.json
diff --git a/lib/common.ml b/lib/common.ml
index 935b2c8b..d3ac6f19 100644
--- a/lib/common.ml
+++ b/lib/common.ml
@@ -72,13 +72,6 @@ let code_of_surrogate_pair i j =
 let utf8_of_surrogate_pair buf i j =
   utf8_of_code buf (code_of_surrogate_pair i j)
 
-let is_object_or_array x =
-  match x with
-      `List _
-    | `Assoc _ -> true
-    | _ -> false
-
-
 type lexer_state = {
   buf : Bi_outbuf.t;
     (* Buffer used to accumulate substrings *)
@@ -116,3 +109,11 @@ let init_lexer ?buf ?fname ?(lnum = 1) () =
     bol = 0;
     fname = fname
   }
+
+type position = {
+  file_name : string option;
+  start_line : int;
+  start_column : int;
+  end_line : int;
+  end_column : int;
+}
diff --git a/lib/common.mli b/lib/common.mli
index 415b3630..52e5dafc 100644
--- a/lib/common.mli
+++ b/lib/common.mli
@@ -36,6 +36,14 @@ val init_lexer :
   unit -> lexer_state
   (** Create a fresh lexer_state record. *)
 
+type position = {
+  file_name : string option;
+  start_line : int;
+  start_column : int;
+  end_line : int;
+  end_column : int;
+}
+  (** The type for code positions. *)
 
 (**/**)
 (* begin undocumented section *)
diff --git a/lib/jbuild b/lib/jbuild
index 3f82564b..28d55429 100644
--- a/lib/jbuild
+++ b/lib/jbuild
@@ -13,7 +13,8 @@
     write2.ml
     common.ml
     util.ml
-    type.ml))
+    type.ml
+    position.ml))
   (action (run cppo ${<} -o ${@}))))
 
 (rule
diff --git a/lib/position.ml b/lib/position.ml
new file mode 100644
index 00000000..1205f497
--- /dev/null
+++ b/lib/position.ml
@@ -0,0 +1,57 @@
+#ifdef POSITION
+  let project (_, x) = x
+
+  let inject x =
+    let dummy =
+      {
+        file_name = Some "(dummy)";
+        start_line = 0;
+        start_column = 0;
+        end_line = 0;
+        end_column = 0;
+      }
+    in
+    (dummy, x)
+
+  let rec forget_positions ((_, x) : json) =
+    match x with
+    | `Null -> `Null
+    | `Bool b -> `Bool b
+  #ifdef INT
+    | `Int i -> `Int i
+  #endif
+  #ifdef INTLIT
+    | `Intlit s -> `Intlit s
+  #endif
+  #ifdef FLOAT
+    | `Float r -> `Float r
+  #endif
+  #ifdef FLOATLIT
+    | `Floatlit s -> `Floatlit s
+  #endif
+  #ifdef STRING
+    | `String s -> `String s
+  #endif
+  #ifdef STRINGLIT
+    | `Stringlit s -> `Stringlit s
+  #endif
+    | `Assoc assoc -> `Assoc (assoc |> List.map (fun (k, v) -> (k, forget_positions v)))
+    | `List js -> `List (js |> List.map forget_positions)
+  #ifdef TUPLE
+    | `Tuple js -> `Tuple (js |> List.map forget_positions)
+  #endif
+  #ifdef VARIANT
+    | `Variant (s, jopt) ->
+        begin
+          match jopt with
+          | None -> `Variant (s, None)
+          | Some(j) -> `Variant (s, Some(forget_positions j))
+        end
+  #endif
+#else
+  let project x = x
+
+  let inject x = x
+
+  let forget_positions x = x
+#endif
diff --git a/lib/read.mll b/lib/read.mll
index 14f530fe..b0603822 100644
--- a/lib/read.mll
+++ b/lib/read.mll
@@ -22,9 +22,6 @@
       result
   end
 
-  open Printf
-  open Lexing
-
   (* see description in common.mli *)
   type lexer_state = Lexer_state.t = {
     buf : Bi_outbuf.t;
@@ -33,6 +30,52 @@
     mutable fname : string option;
   }
 
+  let get_raw_position v lexbuf =
+    let open Lexing in
+    let fname = v.fname in
+    let offs = lexbuf.lex_abs_pos in
+    let bol = v.bol in
+    let pos1 = offs + lexbuf.lex_start_pos - bol in
+    let pos2 = max pos1 (offs + lexbuf.lex_curr_pos - bol) in
+    (fname, v.lnum, pos1, pos2)
+
+  #ifdef POSITION
+    let range rawpos_start rawpos_end x : json =
+      let open Lexing in
+      let (fname, lnum1, pos1, _) = rawpos_start in
+      let (_, lnum2, _, pos2) = rawpos_end in
+      let pos =
+        {
+          file_name = fname;
+          start_line = lnum1;
+          start_column = pos1;
+          end_line = lnum2;
+          end_column = pos2;
+        }
+      in
+      (pos, x)
+
+    let single v lexbuf x : json =
+      let (fname, lnum, pos1, pos2) = get_raw_position v lexbuf in
+      let pos =
+        {
+          file_name = fname;
+          start_line = lnum;
+          start_column = pos1;
+          end_line = lnum;
+          end_column = pos2;
+        }
+      in
+      (pos, x)
+  #else
+    let range _ _ (x : json) : json = x
+
+    let single _ _ (x : json) : json = x
+  #endif
+
+  open Printf
+  open Lexing
+
   let dec c =
     Char.code c - 48
 
@@ -44,10 +87,7 @@
       | _ -> assert false
 
   let custom_error descr v lexbuf =
-    let offs = lexbuf.lex_abs_pos - 1 in
-    let bol = v.bol in
-    let pos1 = offs + lexbuf.lex_start_pos - bol - 1 in
-    let pos2 = max pos1 (offs + lexbuf.lex_curr_pos - bol) in
+    let (fname, lnum, pos1, pos2) = get_raw_position v lexbuf in
     let file_line =
       match v.fname with
           None -> "Line"
@@ -56,11 +96,11 @@
     in
     let bytes =
       if pos1 = pos2 then
-        sprintf "byte %i" (pos1+1)
+        sprintf "byte %i" pos1
       else
-        sprintf "bytes %i-%i" (pos1+1) (pos2+1)
+        sprintf "bytes %i-%i" pos1 pos2
     in
-    let msg = sprintf "%s %i, %s:\n%s" file_line v.lnum bytes descr in
+    let msg = sprintf "%s %i, %s:\n%s" file_line lnum bytes descr in
     json_error msg
 
 
@@ -101,11 +141,11 @@
 
   let make_positive_int v lexbuf =
     #ifdef INT
-      try `Int (extract_positive_int lexbuf)
+      try single v lexbuf (`Int (extract_positive_int lexbuf))
       with Int_overflow ->
     #endif
       #ifdef INTLIT
-        `Intlit (lexeme lexbuf)
+        single v lexbuf (`Intlit (lexeme lexbuf))
       #else
         lexer_error "Int overflow" v lexbuf
       #endif
@@ -128,11 +168,11 @@
 
   let make_negative_int v lexbuf =
     #ifdef INT
-      try `Int (extract_negative_int lexbuf)
+      try single v lexbuf (`Int (extract_negative_int lexbuf))
       with Int_overflow ->
     #endif
       #ifdef INTLIT
-        `Intlit (lexeme lexbuf)
+        single v lexbuf (`Intlit (lexeme lexbuf))
       #else
         lexer_error "Int overflow" v lexbuf
       #endif
@@ -185,49 +225,54 @@ let optjunk32 = (eof | _ (eof | _ (eof | _ (eof | _ (eof | optjunk28)))))
 let junk = optjunk32
 
 rule read_json v = parse
-  | "true"      { `Bool true }
-  | "false"     { `Bool false }
-  | "null"      { `Null }
+  | "true"      { single v lexbuf (`Bool true) }
+  | "false"     { single v lexbuf (`Bool false) }
+  | "null"      { single v lexbuf (`Null) }
   | "NaN"       {
                   #ifdef FLOAT
-                    `Float nan
+                    single v lexbuf (`Float nan)
                   #elif defined FLOATLIT
-                    `Floatlit "NaN"
+                    single v lexbuf (`Floatlit "NaN")
                   #endif
                 }
   | "Infinity"  {
                   #ifdef FLOAT
-                    `Float infinity
+                    single v lexbuf (`Float infinity)
                   #elif defined FLOATLIT
-                    `Floatlit "Infinity"
+                    single v lexbuf (`Floatlit "Infinity")
                   #endif
                 }
   | "-Infinity" {
                   #ifdef FLOAT
-                    `Float neg_infinity
+                    single v lexbuf (`Float neg_infinity)
                   #elif defined FLOATLIT
-                    `Floatlit "-Infinity"
+                    single v lexbuf (`Floatlit "-Infinity")
                   #endif
                 }
   | '"'         {
                   #ifdef STRING
                     Bi_outbuf.clear v.buf;
-                    `String (finish_string v lexbuf)
+                    let pos_start = get_raw_position v lexbuf in
+                    let (pos_end, s) = finish_string_with_position v lexbuf in
+                    range pos_start pos_end (`String (s))
                   #elif defined STRINGLIT
-                    `Stringlit (finish_stringlit v lexbuf)
+                    let pos_start = get_raw_position v lexbuf in
+                    let (pos_end, s) = finish_stringlit_with_position v lexbuf in
+                    range pos_start pos_end (`Stringlit (s))
                   #endif
                 }
   | positive_int         { make_positive_int v lexbuf }
   | '-' positive_int     { make_negative_int v lexbuf }
   | float       {
                   #ifdef FLOAT
-                    `Float (float_of_string (lexeme lexbuf))
+                    single v lexbuf (`Float (float_of_string (lexeme lexbuf)))
                   #elif defined FLOATLIT
-                    `Floatlit (lexeme lexbuf)
+                    single v lexbuf (`Floatlit (lexeme lexbuf))
                   #endif
                  }
 
   | '{'          { let acc = ref [] in
+                   let pos_start = get_raw_position v lexbuf in
                    try
                      read_space v lexbuf;
                      read_object_end lexbuf;
@@ -248,10 +293,12 @@ rule read_json v = parse
                      done;
                      assert false
                    with End_of_object ->
-                     `Assoc (List.rev !acc)
+                     let pos_end = get_raw_position v lexbuf in
+                     range pos_start pos_end (`Assoc (List.rev !acc))
                  }
 
   | '['          { let acc = ref [] in
+                   let pos_start = get_raw_position v lexbuf in
                    try
                      read_space v lexbuf;
                      read_array_end lexbuf;
@@ -264,12 +311,14 @@ rule read_json v = parse
                      done;
                      assert false
                    with End_of_array ->
-                     `List (List.rev !acc)
+                     let pos_end = get_raw_position v lexbuf in
+                     range pos_start pos_end (`List (List.rev !acc))
                  }
 
   | '('          {
                    #ifdef TUPLE
                      let acc = ref [] in
+                     let pos_start = get_raw_position v lexbuf in
                      try
                        read_space v lexbuf;
                        read_tuple_end lexbuf;
@@ -282,7 +331,8 @@ rule read_json v = parse
                        done;
                        assert false
                      with End_of_tuple ->
-                       `Tuple (List.rev !acc)
+                       let pos_end = get_raw_position v lexbuf in
+                       range pos_start pos_end (`Tuple (List.rev !acc))
                    #else
                      long_error "Invalid token" v lexbuf
                    #endif
@@ -290,10 +340,12 @@ rule read_json v = parse
 
   | '<'          {
                    #ifdef VARIANT
+                     let pos_start = get_raw_position v lexbuf in
                      read_space v lexbuf;
                      let cons = read_ident v lexbuf in
                      read_space v lexbuf;
-                     `Variant (cons, finish_variant v lexbuf)
+                     let pos_end = get_raw_position v lexbuf in
+                     range pos_start pos_end (`Variant (cons, finish_variant v lexbuf))
                    #else
                      long_error "Invalid token" v lexbuf
                    #endif
@@ -307,12 +359,12 @@ rule read_json v = parse
   | _            { long_error "Invalid token" v lexbuf }
 
 
-and finish_string v = parse
-    '"'           { Bi_outbuf.contents v.buf }
+and finish_string_with_position v = parse
+    '"'           { let pos_end = get_raw_position v lexbuf in (pos_end, Bi_outbuf.contents v.buf) }
   | '\\'          { finish_escaped_char v lexbuf;
-                    finish_string v lexbuf }
+                    finish_string_with_position v lexbuf }
   | [^ '"' '\\']+ { add_lexeme v.buf lexbuf;
-                    finish_string v lexbuf }
+                    finish_string_with_position v lexbuf }
   | eof           { custom_error "Unexpected end of input" v lexbuf }
 
 and map_string v f = parse
@@ -360,14 +412,15 @@ and finish_surrogate_pair v x = parse
                        for code point beyond U+FFFF" v lexbuf }
   | eof  { custom_error "Unexpected end of input" v lexbuf }
 
-and finish_stringlit v = parse
+and finish_stringlit_with_position v = parse
     ( '\\' (['"' '\\' '/' 'b' 'f' 'n' 'r' 't'] | 'u' hex hex hex hex)
     | [^'"' '\\'] )* '"'
          { let len = lexbuf.lex_curr_pos - lexbuf.lex_start_pos in
            let s = Bytes.create (len+1) in
+           let pos_end = get_raw_position v lexbuf in
            Bytes.set s 0 '"';
            Bytes.blit lexbuf.lex_buffer lexbuf.lex_start_pos s 1 len;
-           Bytes.to_string s
+           (pos_end, Bytes.to_string s)
          }
   | _    { long_error "Invalid string literal" v lexbuf }
   | eof  { custom_error "Unexpected end of input" v lexbuf }
@@ -455,7 +508,7 @@ and read_int v = parse
                              lexer_error "Int overflow" v lexbuf }
   | '"'                  { (* Support for double-quoted "ints" *)
                            Bi_outbuf.clear v.buf;
-                           let s = finish_string v lexbuf in
+                           let (_, s) = finish_string_with_position v lexbuf in
                            try
                              (* Any OCaml-compliant int will pass,
                                 including hexadecimal and octal notations,
@@ -476,7 +529,7 @@ and read_int32 v = parse
                              lexer_error "Int32 overflow" v lexbuf }
   | '"'                  { (* Support for double-quoted "ints" *)
                            Bi_outbuf.clear v.buf;
-                           let s = finish_string v lexbuf in
+                           let (_, s) = finish_string_with_position v lexbuf in
                            try
                              (* Any OCaml-compliant int will pass,
                                 including hexadecimal and octal notations,
@@ -497,7 +550,7 @@ and read_int64 v = parse
                              lexer_error "Int32 overflow" v lexbuf }
   | '"'                  { (* Support for double-quoted "ints" *)
                            Bi_outbuf.clear v.buf;
-                           let s = finish_string v lexbuf in
+                           let (_, s) = finish_string_with_position v lexbuf in
                            try
                              (* Any OCaml-compliant int will pass,
                                 including hexadecimal and octal notations,
@@ -518,7 +571,7 @@ and read_number v = parse
   | "-Infinity" { neg_infinity }
   | number      { float_of_string (lexeme lexbuf) }
   | '"'         { Bi_outbuf.clear v.buf;
-                  let s = finish_string v lexbuf in
+                  let (_, s) = finish_string_with_position v lexbuf in
                   try
                     (* Any OCaml-compliant float will pass,
                        including hexadecimal and octal notations,
@@ -540,13 +593,15 @@ and read_number v = parse
 
 and read_string v = parse
     '"'      { Bi_outbuf.clear v.buf;
-               finish_string v lexbuf }
+               let (_, s) = finish_string_with_position v lexbuf in
+               s }
   | _        { long_error "Expected '\"' but found" v lexbuf }
   | eof      { custom_error "Unexpected end of input" v lexbuf }
 
 and read_ident v = parse
     '"'      { Bi_outbuf.clear v.buf;
-               finish_string v lexbuf }
+               let (_, s) = finish_string_with_position v lexbuf in
+               s }
   | ident as s
              { s }
   | _        { long_error "Expected string or identifier but found" v lexbuf }
@@ -1211,4 +1266,12 @@ and junk = parse
     to_string (from_string s)
 
   let validate_json _path _value = None
+
+  let finish_string v lexbuf =
+    let (_, s) = finish_string_with_position v lexbuf in
+    s
+
+  let finish_stringlit v lexbuf =
+    let (_, s) = finish_stringlit_with_position v lexbuf in
+    s
 }
diff --git a/lib/safe.ml b/lib/safe.ml
index 0db22015..cbeb4a32 100644
--- a/lib/safe.ml
+++ b/lib/safe.ml
@@ -1,5 +1,6 @@
-let rec to_basic : json -> Basic.json = function
-    `Null
+let rec to_basic (x : json) : Basic.json =
+  match project x with
+  | `Null
   | `Bool _
   | `Int _
   | `Float _
diff --git a/lib/type.ml b/lib/type.ml
index aa503669..d62fd238 100644
--- a/lib/type.ml
+++ b/lib/type.ml
@@ -1,6 +1,9 @@
 (** {3 Type of the JSON tree} *)
 
 type json =
+#ifdef POSITION
+  position *
+#endif
     [
     | `Null
     | `Bool of bool
diff --git a/lib/util.ml b/lib/util.ml
index db4574fc..6c36cc72 100644
--- a/lib/util.ml
+++ b/lib/util.ml
@@ -1,6 +1,7 @@
 exception Type_error of string * json
 
-let typeof = function
+let typeof js =
+  match project js with
   | `Assoc _ -> "object"
   | `Bool _ -> "bool"
   | `Float _ -> "float"
@@ -20,88 +21,112 @@ let ( |> ) = ( |> )
 
 let assoc name obj =
   try List.assoc name obj
-  with Not_found -> `Null
+  with Not_found -> inject `Null
 
-let member name = function
+let member name js =
+  match project js with
   | `Assoc obj -> assoc name obj
-  | js -> typerr ("Can't get member '" ^ name ^ "' of non-object type ") js
+  | _ -> typerr ("Can't get member '" ^ name ^ "' of non-object type ") js
 
-let index i = function
-  | `List l as js ->
+let index i js =
+  match project js with
+  | `List l ->
       let len = List.length l in
       let wrapped_index = if i < 0 then len + i else i in
       if wrapped_index < 0 || wrapped_index >= len then
         raise (Undefined ("Index " ^ string_of_int i ^ " out of bounds", js))
       else List.nth l wrapped_index
-  | js -> typerr ("Can't get index " ^ string_of_int i
+  | _ -> typerr ("Can't get index " ^ string_of_int i
                  ^ " of non-array type ") js
 
-let map f = function
-  | `List l -> `List (List.map f l)
-  | js -> typerr "Can't map function over non-array type " js
-
-let to_assoc = function
+let map f js =
+#ifdef POSITION
+  let (pos, x) = js in
+  let posf v = (pos, v) in
+#else
+  let x = js in
+  let posf v = v in
+#endif
+  match x with
+  | `List l -> posf (`List (List.map f l))
+  | _ -> typerr "Can't map function over non-array type " js
+
+let to_assoc js =
+  match project js with
   | `Assoc obj -> obj
-  | js -> typerr "Expected object, got " js
+  | _ -> typerr "Expected object, got " js
 
-let to_option f = function
+let to_option f js =
+  match project js with
   | `Null -> None
-  | x -> Some (f x)
+  | _ -> Some (f js)
 
-let to_bool = function
+let to_bool js =
+  match project js with
   | `Bool b -> b
-  | js -> typerr "Expected bool, got " js
+  | _ -> typerr "Expected bool, got " js
 
-let to_bool_option = function
+let to_bool_option js =
+  match project js with
   | `Bool b -> Some b
   | `Null -> None
-  | js -> typerr "Expected bool or null, got " js
+  | _ -> typerr "Expected bool or null, got " js
 
-let to_number = function
+let to_number js =
+  match project js with
   | `Int i -> float i
   | `Float f -> f
-  | js -> typerr "Expected number, got " js
+  | _ -> typerr "Expected number, got " js
 
-let to_number_option = function
+let to_number_option js =
+  match project js with
   | `Int i -> Some (float i)
   | `Float f -> Some f
   | `Null -> None
-  | js -> typerr "Expected number or null, got " js
+  | _ -> typerr "Expected number or null, got " js
 
-let to_float = function
+let to_float js =
+  match project js with
   | `Float f -> f
-  | js -> typerr "Expected float, got " js
+  | _ -> typerr "Expected float, got " js
 
-let to_float_option = function
+let to_float_option js =
+  match project js with
   | `Float f -> Some f
   | `Null -> None
-  | js -> typerr "Expected float or null, got " js
+  | _ -> typerr "Expected float or null, got " js
 
-let to_int = function
+let to_int js =
+  match project js with
   | `Int i -> i
-  | js -> typerr "Expected int, got " js
+  | _ -> typerr "Expected int, got " js
 
-let to_int_option = function
+let to_int_option js =
+  match project js with
   | `Int i -> Some i
   | `Null -> None
-  | js -> typerr "Expected int or null, got " js
+  | _ -> typerr "Expected int or null, got " js
 
-let to_list = function
+let to_list js =
+  match project js with
   | `List l -> l
-  | js -> typerr "Expected array, got " js
+  | _ -> typerr "Expected array, got " js
 
-let to_string = function
+let to_string js =
+  match project js with
   | `String s -> s
-  | js -> typerr "Expected string, got " js
+  | _ -> typerr "Expected string, got " js
 
-let to_string_option = function
+let to_string_option js =
+  match project js with
   | `String s -> Some s
   | `Null -> None
-  | js -> typerr "Expected string or null, got " js
+  | _ -> typerr "Expected string or null, got " js
 
-let convert_each f = function
+let convert_each f js =
+  match project js with
   | `List l -> List.map f l
-  | js -> typerr "Can't convert each element of non-array type " js
+  | _ -> typerr "Can't convert each element of non-array type " js
 
 
 let rec rev_filter_map f acc l =
@@ -118,8 +143,8 @@ let filter_map f l =
 let rec rev_flatten acc l =
   match l with
       [] -> acc
-    | x :: tl ->
-        match x with
+    | js :: tl ->
+        match project js with
             `List l2 -> rev_flatten (List.rev_append l2 acc) tl
           | _ -> rev_flatten acc tl
 
@@ -127,8 +152,8 @@ let flatten l =
   List.rev (rev_flatten [] l)
 
 let filter_index i l =
-  filter_map (
-    function
+  filter_map (fun js ->
+    match project js with
         `List l ->
           (try Some (List.nth l i)
            with _ -> None)
@@ -136,15 +161,15 @@ let filter_index i l =
   ) l
 
 let filter_list l =
-  filter_map (
-    function
+  filter_map (fun js ->
+    match project js with
         `List l -> Some l
       | _ -> None
   ) l
 
 let filter_member k l =
-  filter_map (
-    function
+  filter_map (fun js ->
+    match project js with
         `Assoc l ->
           (try Some (List.assoc k l)
            with _ -> None)
@@ -152,48 +177,86 @@ let filter_member k l =
   ) l
 
 let filter_assoc l =
-  filter_map (
-    function
+  filter_map (fun js ->
+    match project js with
         `Assoc l -> Some l
       | _ -> None
   ) l
 
 let filter_bool l =
-  filter_map (
-    function
+  filter_map (fun js ->
+    match project js with
         `Bool x -> Some x
       | _ -> None
   ) l
 
 let filter_int l =
-  filter_map (
-    function
+  filter_map (fun js ->
+    match project js with
         `Int x -> Some x
       | _ -> None
   ) l
 
 let filter_float l =
-  filter_map (
-    function
+  filter_map (fun js ->
+    match project js with
         `Float x -> Some x
       | _ -> None
   ) l
 
 let filter_number l =
-  filter_map (
-    function
+  filter_map (fun js ->
+    match project js with
         `Int x -> Some (float x)
       | `Float x -> Some x
       | _ -> None
   ) l
 
 let filter_string l =
-  filter_map (
-    function
+  filter_map (fun js ->
+    match project js with
         `String x -> Some x
       | _ -> None
   ) l
 
+#ifdef POSITION
+let filter_bool_with_pos l =
+  filter_map (fun (pos, v) ->
+    match v with
+        `Bool x -> Some (pos, x)
+      | _ -> None
+  ) l
+
+let filter_int_with_pos l =
+  filter_map (fun (pos, v) ->
+    match v with
+        `Int x -> Some (pos, x)
+      | _ -> None
+  ) l
+
+let filter_float_with_pos l =
+  filter_map (fun (pos, v) ->
+    match v with
+        `Float x -> Some (pos, x)
+      | _ -> None
+  ) l
+
+let filter_number_with_pos l =
+  filter_map (fun (pos, v) ->
+    match v with
+        `Int x -> Some (pos, float x)
+      | `Float x -> Some (pos, x)
+      | _ -> None
+  ) l
+
+let filter_string_with_pos l =
+  filter_map (fun (pos, v) ->
+    match v with
+        `String x -> Some (pos, x)
+      | _ -> None
+  ) l
+#endif
+
 let keys o =
   to_assoc o |> List.map (fun (key, _) -> key)
 
@@ -201,6 +264,15 @@ let values o =
   to_assoc o |> List.map (fun (_, value) -> value)
 
 let combine (first : json) (second : json) =
-  match (first, second) with
-  | (`Assoc a, `Assoc b) -> (`Assoc (a @ b) :  json)
-  | (a, b) -> raise (Invalid_argument "Expected two objects, check inputs")
+#ifdef POSITION
+  let (pos, x) = first in
+  let (_, y) = second in
+  let f v = (pos, v) in
+#else
+  let x = first in
+  let y = second in
+  let f v = v in
+#endif
+  match (x, y) with
+  | (`Assoc a, `Assoc b) -> (f (`Assoc (a @ b)) : json)
+  | (_, _) -> raise (Invalid_argument "Expected two objects, check inputs")
diff --git a/lib/util.mli b/lib/util.mli
index 4d19d96a..5a832022 100644
--- a/lib/util.mli
+++ b/lib/util.mli
@@ -200,3 +200,20 @@ val filter_number : json list -> float list
 
 val filter_string : json list -> string list
   (** Expects JSON strings and unwraps them. *)
+
+#ifdef POSITION
+val filter_bool_with_pos : json list -> (position * bool) list
+  (** Same as [filter_bool], but preserves the code position of the values. *)
+
+val filter_int_with_pos : json list -> (position * int) list
+  (** Same as [filter_int], but preserves the code position of the values. *)
+
+val filter_float_with_pos : json list -> (position * float) list
+  (** Same as [filter_float], but preserves the code position of the values. *)
+
+val filter_number_with_pos : json list -> (position * float) list
+  (** Same as [filter_number], but preserves the code position of the values. *)
+
+val filter_string_with_pos : json list -> (position * string) list
+  (** Same as [filter_string], but preserves the code position of the values. *)
+#endif
diff --git a/lib/write.ml b/lib/write.ml
index 6b0749be..dc6c80ac 100644
--- a/lib/write.ml
+++ b/lib/write.ml
@@ -293,8 +293,8 @@ let iter2 f_elt f_sep x = function
 let f_sep ob =
   Bi_outbuf.add_char ob ','
 
-let rec write_json ob (x : json) =
-  match x with
+let rec write_json ob (js : json) =
+  match project js with
       `Null -> write_null ob ()
     | `Bool b -> write_bool ob b
 #ifdef INT
@@ -360,8 +360,8 @@ and write_variant ob s o =
 #endif
 
 
-let rec write_std_json ob (x : json) =
-  match x with
+let rec write_std_json ob (js : json) =
+  match project js with
       `Null -> write_null ob ()
     | `Bool b -> write_bool ob b
 #ifdef INT
@@ -424,7 +424,14 @@ and write_std_variant ob s o =
 #endif
 
 
-let to_outbuf ?(std = false) ob x =
+let is_object_or_array (js : json) =
+  match project js with
+      `List _
+    | `Assoc _ -> true
+    | _ -> false
+
+
+let to_outbuf ?(std = false) ob (x : json) =
   if std then (
     if not (is_object_or_array x) then
       json_error "Root is not an object or array"
@@ -510,21 +517,28 @@ let stream_to_file ?len ?std file st =
     raise e
 
 
-let rec sort = function
+let rec sort (x : json) : json =
+#ifdef POSITION
+  let (pos, x) = x in
+  let return v = (pos, v) in
+#else
+  let return v = v in
+#endif
+  match x with
   | `Assoc l ->
       let l = List.rev (List.rev_map (fun (k, v) -> (k, sort v)) l) in
-      `Assoc (List.stable_sort (fun (a, _) (b, _) -> String.compare a b) l)
+      return (`Assoc (List.stable_sort (fun (a, _) (b, _) -> String.compare a b) l))
   | `List l ->
-      `List (List.rev (List.rev_map sort l))
+      return (`List (List.rev (List.rev_map sort l)))
 #ifdef TUPLE
   | `Tuple l ->
-      `Tuple (List.rev (List.rev_map sort l))
+      return (`Tuple (List.rev (List.rev_map sort l)))
 #endif
 #ifdef VARIANT
   | `Variant (k, Some v) as x ->
       let v' = sort v in
-      if v == v' then x
+      if v == v' then return x
       else
-        `Variant (k, Some v')
+        return (`Variant (k, Some v'))
 #endif
-  | x -> x
+  | x -> return x
diff --git a/lib/write2.ml b/lib/write2.ml
index 17d83504..d449dea2 100644
--- a/lib/write2.ml
+++ b/lib/write2.ml
@@ -1,11 +1,14 @@
-let pretty_format ?std (x : json) =
+let pretty_format ?std (js : json) =
+  let x = forget_positions js in
   Pretty.format ?std (x :> json_max)
 
-let pretty_print ?std out (x : json) =
-  Easy_format.Pretty.to_formatter out (pretty_format ?std x)
+let pretty_print ?std out (js : json) =
+  Easy_format.Pretty.to_formatter out (pretty_format ?std js)
 
-let pretty_to_string ?std (x : json) =
+let pretty_to_string ?std (js : json) =
+  let x = forget_positions js in
   Pretty.to_string ?std (x :> json_max)
 
-let pretty_to_channel ?std oc (x : json) =
+let pretty_to_channel ?std oc (js : json) =
+  let x = forget_positions js in
   Pretty.to_channel ?std oc (x :> json_max)
diff --git a/lib/yojson.cppo.ml b/lib/yojson.cppo.ml
index 1a3321f4..42459e54 100644
--- a/lib/yojson.cppo.ml
+++ b/lib/yojson.cppo.ml
@@ -9,6 +9,7 @@
 #define TUPLE
 #define VARIANT
 #include "type.ml"
+#include "position.ml"
 type json_max = json
 #include "write.ml"
 module Pretty =
@@ -31,6 +32,7 @@ struct
 #define FLOAT
 #define STRING
 #include "type.ml"
+#include "position.ml"
 #include "write.ml"
 #include "write2.ml"
 #include "read.ml"
@@ -52,6 +54,7 @@ struct
 #define TUPLE
 #define VARIANT
 #include "type.ml"
+#include "position.ml"
 #include "safe.ml"
 #include "write.ml"
 #include "write2.ml"
@@ -76,6 +79,7 @@ struct
 #define TUPLE
 #define VARIANT
 #include "type.ml"
+#include "position.ml"
 #include "write.ml"
 #include "write2.ml"
 #include "read.ml"
@@ -85,3 +89,31 @@ struct
 #undef TUPLE
 #undef VARIANT
 end
+
+module SafePos =
+struct
+#define POSITION
+#define INT
+#define INTLIT
+#define FLOAT
+#define STRING
+#define TUPLE
+#define VARIANT
+#include "type.ml"
+#include "position.ml"
+#include "safe.ml"
+#include "write.ml"
+#include "write2.ml"
+#include "read.ml"
+module Util =
+struct
+  #include "util.ml"
+end
+#undef POSITION
+#undef INT
+#undef INTLIT
+#undef FLOAT
+#undef STRING
+#undef TUPLE
+#undef VARIANT
+end
diff --git a/lib/yojson.cppo.mli b/lib/yojson.cppo.mli
index ebafeb3f..5bce1916 100644
--- a/lib/yojson.cppo.mli
+++ b/lib/yojson.cppo.mli
@@ -6,7 +6,7 @@
    The design goals of Yojson are the following:
    - Reducing inter-package dependencies by the use of polymorphic
    variants for the JSON tree type.
-   - Allowing type-aware serializers/deserializers 
+   - Allowing type-aware serializers/deserializers
    to read and write directly without going through a generic JSON tree,
    for efficiency purposes.
    Readers and writers of all JSON syntaxic elements are provided
@@ -15,7 +15,7 @@
    - Providing optional extensions of the JSON syntax.
    These extensions include comments, arbitrary strings,
    optional quotes around field names, tuples and variants.
-   
+
    @author Martin Jambon
    @see <http://json.org> JSON specification
  *)
@@ -60,10 +60,10 @@ sig
 (**
    This module supports a specific syntax for variants and tuples
    in addition to the standard JSON nodes.
-   Arbitrary integers are supported and represented as a decimal string 
+   Arbitrary integers are supported and represented as a decimal string
    using [`Intlit] when they cannot be represented using OCaml's int type.
 
-   This module is recommended for intensive use 
+   This module is recommended for intensive use
    or OCaml-friendly use of JSON.
 *)
 
@@ -140,3 +140,41 @@ type json_max = json
 #undef TUPLE
 #undef VARIANT
 
+(** {1 Multipurpose JSON tree type} *)
+
+module SafePos :
+sig
+(**
+   This module supports a specific syntax for variants and tuples
+   in addition to the standard JSON nodes.
+   Arbitrary integers are supported and represented as a decimal string
+   using [`Intlit] when they cannot be represented using OCaml's int type.
+
+   This module is recommended for intensive use
+   or OCaml-friendly use of JSON.
+*)
+
+#define POSITION
+#define INT
+#define INTLIT
+#define FLOAT
+#define STRING
+#define TUPLE
+#define VARIANT
+#include "type.ml"
+#include "safe.mli"
+#include "write.mli"
+#include "write2.mli"
+#include "read.mli"
+module Util :
+sig
+  #include "util.mli"
+end
+#undef POSITION
+#undef INT
+#undef INTLIT
+#undef FLOAT
+#undef STRING
+#undef TUPLE
+#undef VARIANT
+end