diff --git a/jscomp/js_config.ml b/jscomp/js_config.ml
index 8e933328d7..93167bcd95 100644
--- a/jscomp/js_config.ml
+++ b/jscomp/js_config.ml
@@ -146,7 +146,7 @@ let runtime_set = String_set.of_list [
 let prim = "Caml_primitive" 
 
 let builtin_exceptions = "Caml_builtin_exceptions"
-
+let exceptions = "Caml_exceptions"
 
 let io = "Caml_io"
 
diff --git a/jscomp/js_config.mli b/jscomp/js_config.mli
index 8e455ac62a..67803e6f7f 100644
--- a/jscomp/js_config.mli
+++ b/jscomp/js_config.mli
@@ -37,7 +37,7 @@ val stdlib_set : String_set.t
 val prim : string 
 
 val builtin_exceptions : string
-
+val exceptions : string
 val io : string
 
 val oo : string
diff --git a/jscomp/js_of_lam_exception.ml b/jscomp/js_of_lam_exception.ml
index 740e9cc774..b67258015f 100644
--- a/jscomp/js_of_lam_exception.ml
+++ b/jscomp/js_of_lam_exception.ml
@@ -39,20 +39,15 @@ let match_exception_def (args : J.expression list) =
       None
   | _ -> None
 
-(* Sync up with [caml_set_oo_id] *)
+(* Sync up with [caml_set_oo_id] 
+   Note if we inline {!Caml_exceptions.create}, 
+   it seems can be useful for optimizations in theory, 
+   in practice, it never happen, since the pattern match 
+   never dig into it internally, so maybe {!Obj.set_tag} 
+   is not necessary at all
+*)
 let make_exception exception_str mutable_flag : J.expression = 
-  { expression_desc = 
-      Caml_block (
-        [exception_str ;
-         E.runtime_call Js_config.builtin_exceptions "get_id" []
-         ],  
-        mutable_flag,
-        (* TODO: combined with `_001` optimization *)
-        E.obj_int_tag_literal (* (Obj.object_tag) *),
-        Blk_na                    
-      );
-    comment = None
-  }
+  E.runtime_call Js_config.exceptions Literals.create [exception_str]
 
 
 
@@ -70,5 +65,5 @@ let caml_set_oo_id args =
          If we can guarantee this code path is never hit, we can do 
          a better job for encoding of exception and extension?
       *)
-      E.runtime_call Js_config.builtin_exceptions "caml_set_oo_id" args 
+      E.runtime_call Js_config.exceptions "caml_set_oo_id" args 
     end
diff --git a/jscomp/literals.ml b/jscomp/literals.ml
index 126e18b482..3e9a7bd709 100644
--- a/jscomp/literals.ml
+++ b/jscomp/literals.ml
@@ -30,3 +30,5 @@ let prim = "prim"
 let param = "param"
 let partial_arg = "partial_arg"
 let tmp = "tmp"
+
+let create = "create" (* {!Caml_exceptions.create}*)
diff --git a/jscomp/literals.mli b/jscomp/literals.mli
index df0cb036db..f3045aebcd 100644
--- a/jscomp/literals.mli
+++ b/jscomp/literals.mli
@@ -31,3 +31,5 @@ val prim : string
 
 (**temporary varaible used in {!Js_ast_util} *)
 val tmp : string 
+
+val create : string 
diff --git a/jscomp/runtime/.depend b/jscomp/runtime/.depend
index 70b3df2c7e..99e2ae35fa 100644
--- a/jscomp/runtime/.depend
+++ b/jscomp/runtime/.depend
@@ -1,6 +1,7 @@
 caml_array.cmi :
 caml_bigarray.cmi :
 caml_builtin_exceptions.cmi :
+caml_exceptions.cmi : caml_builtin_exceptions.cmi
 caml_float.cmi :
 caml_format.cmi :
 caml_hash.cmi :
@@ -23,6 +24,8 @@ caml_builtin_exceptions.cmo : caml_builtin_exceptions.cmi
 caml_builtin_exceptions.cmx : caml_builtin_exceptions.cmi
 caml_curry.cmo : js.cmo caml_oo.cmi
 caml_curry.cmx : js.cmx caml_oo.cmx
+caml_exceptions.cmo : caml_builtin_exceptions.cmi caml_exceptions.cmi
+caml_exceptions.cmx : caml_builtin_exceptions.cmx caml_exceptions.cmi
 caml_float.cmo : typed_array.cmo js.cmo caml_float.cmi
 caml_float.cmx : typed_array.cmx js.cmx caml_float.cmi
 caml_format.cmo : js.cmo caml_utils.cmi caml_format.cmi
@@ -69,6 +72,8 @@ caml_builtin_exceptions.cmo : caml_builtin_exceptions.cmi
 caml_builtin_exceptions.cmj : caml_builtin_exceptions.cmi
 caml_curry.cmo : js.cmo caml_oo.cmi
 caml_curry.cmj : js.cmj caml_oo.cmj
+caml_exceptions.cmo : caml_builtin_exceptions.cmi caml_exceptions.cmi
+caml_exceptions.cmj : caml_builtin_exceptions.cmj caml_exceptions.cmi
 caml_float.cmo : typed_array.cmo js.cmo caml_float.cmi
 caml_float.cmj : typed_array.cmj js.cmj caml_float.cmi
 caml_format.cmo : js.cmo caml_utils.cmi caml_format.cmi
diff --git a/jscomp/runtime/caml_builtin_exceptions.js b/jscomp/runtime/caml_builtin_exceptions.js
index 10fe3322b1..39f578692b 100644
--- a/jscomp/runtime/caml_builtin_exceptions.js
+++ b/jscomp/runtime/caml_builtin_exceptions.js
@@ -2,87 +2,62 @@
 'use strict';
 
 
-var id = [0];
-
-function caml_set_oo_id(b) {
-  b[1] = id[0];
-  id[0] += 1;
-  return b;
-}
-
-function get_id() {
-  id[0] += 1;
-  return id[0];
-}
-
 var out_of_memory = /* tuple */[
-  248,
   "Out_of_memory",
   0
 ];
 
 var sys_error = /* tuple */[
-  248,
   "Sys_error",
   -1
 ];
 
 var failure = /* tuple */[
-  248,
   "Failure",
   -2
 ];
 
 var invalid_argument = /* tuple */[
-  248,
   "Invalid_argument",
   -3
 ];
 
 var end_of_file = /* tuple */[
-  248,
   "End_of_file",
   -4
 ];
 
 var division_by_zero = /* tuple */[
-  248,
   "Division_by_zero",
   -5
 ];
 
 var not_found = /* tuple */[
-  248,
   "Not_found",
   -6
 ];
 
 var match_failure = /* tuple */[
-  248,
   "Match_failure",
   -7
 ];
 
 var stack_overflow = /* tuple */[
-  248,
   "Stack_overflow",
   -8
 ];
 
 var sys_blocked_io = /* tuple */[
-  248,
   "Sys_blocked_io",
   -9
 ];
 
 var assert_failure = /* tuple */[
-  248,
   "Assert_failure",
   -10
 ];
 
 var undefined_recursive_module = /* tuple */[
-  248,
   "Undefined_recursive_module",
   -11
 ];
@@ -99,6 +74,4 @@ exports.stack_overflow             = stack_overflow;
 exports.sys_blocked_io             = sys_blocked_io;
 exports.assert_failure             = assert_failure;
 exports.undefined_recursive_module = undefined_recursive_module;
-exports.caml_set_oo_id             = caml_set_oo_id;
-exports.get_id                     = get_id;
 /* No side effect */
diff --git a/jscomp/runtime/caml_builtin_exceptions.ml b/jscomp/runtime/caml_builtin_exceptions.ml
index 92799b88a9..41ac6000a3 100644
--- a/jscomp/runtime/caml_builtin_exceptions.ml
+++ b/jscomp/runtime/caml_builtin_exceptions.ml
@@ -18,43 +18,23 @@
 
 (* Author: Hongbo Zhang  *)
 
-type exception_block = int * string * int 
-let out_of_memory = 248, "Out_of_memory", 0
-let sys_error = 248, "Sys_error", -1
-let failure = 248, "Failure", -2
-let invalid_argument = 248, "Invalid_argument", -3
-let end_of_file = 248, "End_of_file",-4
-let division_by_zero = 248, "Division_by_zero", -5
-let not_found = 248, "Not_found", -6
-let match_failure = 248, "Match_failure", -7
-let stack_overflow = 248, "Stack_overflow",-8
-let sys_blocked_io = 248, "Sys_blocked_io", -9
-let assert_failure = 248, "Assert_failure", -10
-let undefined_recursive_module = 248, "Undefined_recursive_module", -11
-
-
-
-(* Exported for better inlining *)
-(* It's common that we have <code> a = caml_set_oo_id([248,"string",0])</code> *)
-(* This can be inlined as <code> a = caml_set_oo_id([248,"tag", caml_oo_last_id++])</code> *)
- (* @type {number} *)
-
-let id = ref 0n
-
-
-(* see  #251
-   {[
-     CAMLprim value caml_set_oo_id (value obj) {
-       Field(obj, 1) = oo_last_id;
-       oo_last_id += 2;
-       return obj;
-     }
-
-   ]}*)
-let caml_set_oo_id (b : exception_block)  = 
-    Obj.set_field (Obj.repr b) 1 (Obj.repr !id);
-    id := Nativeint.add !id  1n; 
-    b
-
-let get_id () = 
-  id := Nativeint.add !id 1n; !id
+type exception_block = string * nativeint 
+
+
+let out_of_memory =  "Out_of_memory", 0n
+let sys_error = "Sys_error", -1n
+let failure =  "Failure", -2n
+let invalid_argument =  "Invalid_argument", -3n
+let end_of_file = "End_of_file",-4n
+let division_by_zero =  "Division_by_zero", -5n
+let not_found = "Not_found", -6n
+let match_failure =  "Match_failure", -7n
+let stack_overflow =  "Stack_overflow",-8n
+let sys_blocked_io =  "Sys_blocked_io", -9n
+let assert_failure =  "Assert_failure", -10n
+let undefined_recursive_module =  "Undefined_recursive_module", -11n
+
+(* TODO: 
+   1. is it necessary to tag [248] here
+   2. is it okay to remove the negative value
+*)
diff --git a/jscomp/runtime/caml_builtin_exceptions.mli b/jscomp/runtime/caml_builtin_exceptions.mli
index 95ced5fe03..b03b74718b 100644
--- a/jscomp/runtime/caml_builtin_exceptions.mli
+++ b/jscomp/runtime/caml_builtin_exceptions.mli
@@ -1,4 +1,4 @@
-type exception_block = int * string * int 
+type exception_block =  string * nativeint
 val out_of_memory : exception_block              
 val sys_error  : exception_block                                
 val failure : exception_block                                  
@@ -12,6 +12,5 @@ val sys_blocked_io : exception_block
 val assert_failure : exception_block                          
 val undefined_recursive_module : exception_block              
 
-val caml_set_oo_id : exception_block -> exception_block
-val get_id : unit -> nativeint
+
  
diff --git a/jscomp/runtime/caml_exceptions.js b/jscomp/runtime/caml_exceptions.js
index c55c31c6b0..3680da98a5 100644
--- a/jscomp/runtime/caml_exceptions.js
+++ b/jscomp/runtime/caml_exceptions.js
@@ -1,56 +1,31 @@
 // Generated CODE, PLEASE EDIT WITH CARE
 'use strict';
 
-var Caml_builtin_exceptions = require("./caml_builtin_exceptions");
 
-function caml_raise_sys_error(msg) {
-  throw [
-        Caml_builtin_exceptions.sys_error,
-        msg
-      ];
-}
-
-function caml_failwith(s) {
-  throw [
-        Caml_builtin_exceptions.failure,
-        s
-      ];
-}
-
-function caml_invalid_argument(s) {
-  throw [
-        Caml_builtin_exceptions.invalid_argument,
-        s
-      ];
-}
-
-function caml_array_bound_error() {
-  throw [
-        Caml_builtin_exceptions.invalid_argument,
-        "index out of bounds"
-      ];
-}
+var id = [0];
 
-function caml_raise_zero_divide() {
-  throw Caml_builtin_exceptions.division_by_zero;
+function caml_set_oo_id(b) {
+  b[1] = id[0];
+  id[0] += 1;
+  return b;
 }
 
-function caml_raise_not_found() {
-  throw Caml_builtin_exceptions.not_found;
+function get_id() {
+  id[0] += 1;
+  return id[0];
 }
 
-function caml_undef_module(loc) {
-  throw [
-        Caml_builtin_exceptions.undefined_recursive_module,
-        loc
-      ];
+function create(str) {
+  var v_001 = get_id(/* () */0);
+  var v = /* tuple */[
+    str,
+    v_001
+  ];
+  v.tag = 248;
+  return v;
 }
 
-exports.caml_raise_sys_error   = caml_raise_sys_error;
-exports.caml_failwith          = caml_failwith;
-exports.caml_invalid_argument  = caml_invalid_argument;
-exports.caml_array_bound_error = caml_array_bound_error;
-exports.caml_raise_zero_divide = caml_raise_zero_divide;
-exports.caml_raise_not_found   = caml_raise_not_found;
-exports.caml_undef_module      = caml_undef_module;
+exports.caml_set_oo_id = caml_set_oo_id;
+exports.get_id         = get_id;
+exports.create         = create;
 /* No side effect */
diff --git a/jscomp/runtime/caml_exceptions.ml b/jscomp/runtime/caml_exceptions.ml
new file mode 100644
index 0000000000..0ed32cd981
--- /dev/null
+++ b/jscomp/runtime/caml_exceptions.ml
@@ -0,0 +1,52 @@
+(* BuckleScript compiler
+ * Copyright (C) 2015-2016 Bloomberg Finance L.P.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation, with linking exception;
+ * either version 2.1 of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ *)
+
+(* Author: Hongbo Zhang *)
+
+(** 
+   Could be exported for better inlining
+   It's common that we have 
+   {[ a = caml_set_oo_id([248,"string",0]) ]}
+   This can be inlined as 
+   {[ a = caml_set_oo_id([248,"tag", caml_oo_last_id++]) ]}
+*)
+
+let id = ref 0n
+
+
+(* see  #251
+   {[
+     CAMLprim value caml_set_oo_id (value obj) {
+       Field(obj, 1) = oo_last_id;
+       oo_last_id += 2;
+       return obj;
+     }
+
+   ]}*)
+let caml_set_oo_id (b : Caml_builtin_exceptions.exception_block)  = 
+    Obj.set_field (Obj.repr b) 1 (Obj.repr !id);
+    id := Nativeint.add !id  1n; 
+    b
+
+let get_id () = 
+  id := Nativeint.add !id 1n; !id
+
+let create (str : string) : Caml_builtin_exceptions.exception_block = 
+  let v = ( str, get_id ()) in 
+  Obj.set_tag (Obj.repr v) 248 (* Obj.object_tag*);
+  v 
diff --git a/jscomp/runtime/caml_exceptions.mli b/jscomp/runtime/caml_exceptions.mli
new file mode 100644
index 0000000000..decac8faa4
--- /dev/null
+++ b/jscomp/runtime/caml_exceptions.mli
@@ -0,0 +1,27 @@
+(* BuckleScript compiler
+ * Copyright (C) 2015-2016 Bloomberg Finance L.P.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation, with linking exception;
+ * either version 2.1 of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ *)
+
+(* Author: Hongbo Zhang *)
+
+
+val caml_set_oo_id :
+  Caml_builtin_exceptions.exception_block -> Caml_builtin_exceptions.exception_block
+
+val get_id : unit -> nativeint
+
+val create : string -> Caml_builtin_exceptions.exception_block
diff --git a/jscomp/runtime/runtime.mllib b/jscomp/runtime/runtime.mllib
index b901a85033..b2eec47125 100644
--- a/jscomp/runtime/runtime.mllib
+++ b/jscomp/runtime/runtime.mllib
@@ -5,6 +5,7 @@ caml_oo
 caml_obj
 caml_int64
 caml_builtin_exceptions
+caml_exceptions
 caml_utils
 caml_sys
 caml_io
diff --git a/jscomp/stdlib/arg.js b/jscomp/stdlib/arg.js
index cb7917d1a1..21b7ef0e9f 100644
--- a/jscomp/stdlib/arg.js
+++ b/jscomp/stdlib/arg.js
@@ -1,9 +1,10 @@
 // Generated CODE, PLEASE EDIT WITH CARE
 'use strict';
 
-var Caml_builtin_exceptions = require("../runtime/caml_builtin_exceptions");
 var Caml_obj                = require("../runtime/caml_obj");
+var Caml_builtin_exceptions = require("../runtime/caml_builtin_exceptions");
 var Bytes                   = require("./bytes");
+var Caml_exceptions         = require("../runtime/caml_exceptions");
 var Pervasives              = require("./pervasives");
 var Caml_format             = require("../runtime/caml_format");
 var Sys                     = require("./sys");
@@ -14,26 +15,11 @@ var $$String                = require("./string");
 var List                    = require("./list");
 var Caml_string             = require("../runtime/caml_string");
 
-var Bad = {
-  0: "Arg.Bad",
-  1: Caml_builtin_exceptions.get_id(),
-  length: 2,
-  tag: 248
-};
+var Bad = Caml_exceptions.create("Arg.Bad");
 
-var Help = {
-  0: "Arg.Help",
-  1: Caml_builtin_exceptions.get_id(),
-  length: 2,
-  tag: 248
-};
+var Help = Caml_exceptions.create("Arg.Help");
 
-var Stop = {
-  0: "Arg.Stop",
-  1: Caml_builtin_exceptions.get_id(),
-  length: 2,
-  tag: 248
-};
+var Stop = Caml_exceptions.create("Arg.Stop");
 
 function assoc3(x, _l) {
   while(true) {
diff --git a/jscomp/stdlib/array.js b/jscomp/stdlib/array.js
index d26055b79b..e60ed6a016 100644
--- a/jscomp/stdlib/array.js
+++ b/jscomp/stdlib/array.js
@@ -2,6 +2,7 @@
 'use strict';
 
 var Caml_builtin_exceptions = require("../runtime/caml_builtin_exceptions");
+var Caml_exceptions         = require("../runtime/caml_exceptions");
 var Caml_array              = require("../runtime/caml_array");
 var Caml_curry              = require("../runtime/caml_curry");
 
@@ -218,12 +219,7 @@ function fold_right(f, a, x) {
   return r;
 }
 
-var Bottom = {
-  0: "Array.Bottom",
-  1: Caml_builtin_exceptions.get_id(),
-  length: 2,
-  tag: 248
-};
+var Bottom = Caml_exceptions.create("Array.Bottom");
 
 function sort(cmp, a) {
   var maxson = function (l, i) {
diff --git a/jscomp/stdlib/camlinternalFormat.js b/jscomp/stdlib/camlinternalFormat.js
index 504ed470a6..b26a26e0ec 100644
--- a/jscomp/stdlib/camlinternalFormat.js
+++ b/jscomp/stdlib/camlinternalFormat.js
@@ -7,6 +7,7 @@ var Caml_obj                 = require("../runtime/caml_obj");
 var Caml_io                  = require("../runtime/caml_io");
 var Caml_float               = require("../runtime/caml_float");
 var Pervasives               = require("./pervasives");
+var Caml_exceptions          = require("../runtime/caml_exceptions");
 var Caml_format              = require("../runtime/caml_format");
 var Char                     = require("./char");
 var Sys                      = require("./sys");
@@ -2236,12 +2237,7 @@ function fmtty_of_precision_fmtty(prec, fmtty) {
   }
 }
 
-var Type_mismatch = {
-  0: "CamlinternalFormat.Type_mismatch",
-  1: Caml_builtin_exceptions.get_id(),
-  length: 2,
-  tag: 248
-};
+var Type_mismatch = Caml_exceptions.create("CamlinternalFormat.Type_mismatch");
 
 function type_padding(pad, fmtty) {
   if (typeof pad === "number") {
diff --git a/jscomp/stdlib/camlinternalLazy.js b/jscomp/stdlib/camlinternalLazy.js
index 5da5446b5f..ac002f8df1 100644
--- a/jscomp/stdlib/camlinternalLazy.js
+++ b/jscomp/stdlib/camlinternalLazy.js
@@ -1,16 +1,11 @@
 // Generated CODE, PLEASE EDIT WITH CARE
 'use strict';
 
-var Caml_builtin_exceptions = require("../runtime/caml_builtin_exceptions");
-var Obj                     = require("./obj");
-var Caml_curry              = require("../runtime/caml_curry");
+var Obj             = require("./obj");
+var Caml_exceptions = require("../runtime/caml_exceptions");
+var Caml_curry      = require("../runtime/caml_curry");
 
-var Undefined = {
-  0: "CamlinternalLazy.Undefined",
-  1: Caml_builtin_exceptions.get_id(),
-  length: 2,
-  tag: 248
-};
+var Undefined = Caml_exceptions.create("CamlinternalLazy.Undefined");
 
 function raise_undefined() {
   throw Undefined;
diff --git a/jscomp/stdlib/camlinternalOO.js b/jscomp/stdlib/camlinternalOO.js
index c04aaa82e9..dbf9328b0a 100644
--- a/jscomp/stdlib/camlinternalOO.js
+++ b/jscomp/stdlib/camlinternalOO.js
@@ -1,9 +1,10 @@
 // Generated CODE, PLEASE EDIT WITH CARE
 'use strict';
 
-var Caml_builtin_exceptions = require("../runtime/caml_builtin_exceptions");
 var Caml_obj                = require("../runtime/caml_obj");
+var Caml_builtin_exceptions = require("../runtime/caml_builtin_exceptions");
 var Obj                     = require("./obj");
+var Caml_exceptions         = require("../runtime/caml_exceptions");
 var Caml_oo                 = require("../runtime/caml_oo");
 var Sys                     = require("./sys");
 var Caml_primitive          = require("../runtime/caml_primitive");
@@ -14,7 +15,7 @@ var Caml_string             = require("../runtime/caml_string");
 var List                    = require("./list");
 
 function copy(o) {
-  return Caml_builtin_exceptions.caml_set_oo_id(Caml_obj.caml_obj_dup(o));
+  return Caml_exceptions.caml_set_oo_id(Caml_obj.caml_obj_dup(o));
 }
 
 var params = /* record */[
@@ -878,7 +879,7 @@ function create_object(table) {
     tag: Obj.object_tag
   };
   obj[0] = table[/* methods */1];
-  return Caml_builtin_exceptions.caml_set_oo_id(obj);
+  return Caml_exceptions.caml_set_oo_id(obj);
 }
 
 function create_object_opt(obj_0, table) {
@@ -891,7 +892,7 @@ function create_object_opt(obj_0, table) {
       tag: Obj.object_tag
     };
     obj[0] = table[/* methods */1];
-    return Caml_builtin_exceptions.caml_set_oo_id(obj);
+    return Caml_exceptions.caml_set_oo_id(obj);
   }
 }
 
diff --git a/jscomp/stdlib/format.js b/jscomp/stdlib/format.js
index cc448a1433..43c6a19228 100644
--- a/jscomp/stdlib/format.js
+++ b/jscomp/stdlib/format.js
@@ -1,10 +1,11 @@
 // Generated CODE, PLEASE EDIT WITH CARE
 'use strict';
 
-var Caml_builtin_exceptions = require("../runtime/caml_builtin_exceptions");
 var Caml_obj                = require("../runtime/caml_obj");
+var Caml_builtin_exceptions = require("../runtime/caml_builtin_exceptions");
 var Bytes                   = require("./bytes");
 var Caml_io                 = require("../runtime/caml_io");
+var Caml_exceptions         = require("../runtime/caml_exceptions");
 var Pervasives              = require("./pervasives");
 var Buffer                  = require("./buffer");
 var Caml_curry              = require("../runtime/caml_curry");
@@ -30,12 +31,7 @@ function add_queue(x, q) {
   }
 }
 
-var Empty_queue = {
-  0: "Format.Empty_queue",
-  1: Caml_builtin_exceptions.get_id(),
-  length: 2,
-  tag: 248
-};
+var Empty_queue = Caml_exceptions.create("Format.Empty_queue");
 
 function peek_queue(param) {
   var match = param[/* body */1];
diff --git a/jscomp/stdlib/parsing.js b/jscomp/stdlib/parsing.js
index 8c7d78a927..a8d7f7ea9e 100644
--- a/jscomp/stdlib/parsing.js
+++ b/jscomp/stdlib/parsing.js
@@ -1,27 +1,17 @@
 // Generated CODE, PLEASE EDIT WITH CARE
 'use strict';
 
-var Caml_builtin_exceptions = require("../runtime/caml_builtin_exceptions");
-var Caml_obj                = require("../runtime/caml_obj");
-var Caml_parser             = require("../runtime/caml_parser");
-var Lexing                  = require("./lexing");
-var Caml_array              = require("../runtime/caml_array");
-var $$Array                 = require("./array");
-var Caml_curry              = require("../runtime/caml_curry");
-
-var YYexit = {
-  0: "Parsing.YYexit",
-  1: Caml_builtin_exceptions.get_id(),
-  length: 2,
-  tag: 248
-};
-
-var Parse_error = {
-  0: "Parsing.Parse_error",
-  1: Caml_builtin_exceptions.get_id(),
-  length: 2,
-  tag: 248
-};
+var Caml_obj        = require("../runtime/caml_obj");
+var Caml_parser     = require("../runtime/caml_parser");
+var Caml_exceptions = require("../runtime/caml_exceptions");
+var Lexing          = require("./lexing");
+var Caml_array      = require("../runtime/caml_array");
+var $$Array         = require("./array");
+var Caml_curry      = require("../runtime/caml_curry");
+
+var YYexit = Caml_exceptions.create("Parsing.YYexit");
+
+var Parse_error = Caml_exceptions.create("Parsing.Parse_error");
 
 var env = /* record */[
   Caml_array.caml_make_vect(100, 0),
diff --git a/jscomp/stdlib/pervasives.js b/jscomp/stdlib/pervasives.js
index 560e15979f..9bd2f8ac0a 100644
--- a/jscomp/stdlib/pervasives.js
+++ b/jscomp/stdlib/pervasives.js
@@ -4,6 +4,7 @@
 var Caml_builtin_exceptions  = require("../runtime/caml_builtin_exceptions");
 var Caml_obj                 = require("../runtime/caml_obj");
 var Caml_io                  = require("../runtime/caml_io");
+var Caml_exceptions          = require("../runtime/caml_exceptions");
 var Caml_format              = require("../runtime/caml_format");
 var Caml_primitive           = require("../runtime/caml_primitive");
 var CamlinternalFormatBasics = require("./camlinternalFormatBasics");
@@ -24,12 +25,7 @@ function invalid_arg(s) {
       ];
 }
 
-var Exit = {
-  0: "Pervasives.Exit",
-  1: Caml_builtin_exceptions.get_id(),
-  length: 2,
-  tag: 248
-};
+var Exit = Caml_exceptions.create("Pervasives.Exit");
 
 function min(x, y) {
   if (Caml_obj.caml_lessequal(x, y)) {
diff --git a/jscomp/stdlib/queue.js b/jscomp/stdlib/queue.js
index 22fd910d01..8a48388f85 100644
--- a/jscomp/stdlib/queue.js
+++ b/jscomp/stdlib/queue.js
@@ -1,16 +1,11 @@
 // Generated CODE, PLEASE EDIT WITH CARE
 'use strict';
 
-var Caml_builtin_exceptions = require("../runtime/caml_builtin_exceptions");
-var Caml_obj                = require("../runtime/caml_obj");
-var Caml_curry              = require("../runtime/caml_curry");
-
-var Empty = {
-  0: "Queue.Empty",
-  1: Caml_builtin_exceptions.get_id(),
-  length: 2,
-  tag: 248
-};
+var Caml_obj        = require("../runtime/caml_obj");
+var Caml_exceptions = require("../runtime/caml_exceptions");
+var Caml_curry      = require("../runtime/caml_curry");
+
+var Empty = Caml_exceptions.create("Queue.Empty");
 
 function create() {
   return /* record */[
diff --git a/jscomp/stdlib/scanf.js b/jscomp/stdlib/scanf.js
index cc1cc00684..8df89edd9c 100644
--- a/jscomp/stdlib/scanf.js
+++ b/jscomp/stdlib/scanf.js
@@ -4,6 +4,7 @@
 var Caml_builtin_exceptions  = require("../runtime/caml_builtin_exceptions");
 var Bytes                    = require("./bytes");
 var Pervasives               = require("./pervasives");
+var Caml_exceptions          = require("../runtime/caml_exceptions");
 var Caml_format              = require("../runtime/caml_format");
 var Printf                   = require("./printf");
 var Caml_primitive           = require("../runtime/caml_primitive");
@@ -268,12 +269,7 @@ function close_in(ib) {
   }
 }
 
-var Scan_failure = {
-  0: "Scanf.Scan_failure",
-  1: Caml_builtin_exceptions.get_id(),
-  length: 2,
-  tag: 248
-};
+var Scan_failure = Caml_exceptions.create("Scanf.Scan_failure");
 
 function bad_input_escape(c) {
   var s = Caml_curry.app1(Printf.sprintf(/* Format */[
diff --git a/jscomp/stdlib/stack.js b/jscomp/stdlib/stack.js
index 2ca6f0dc01..6a9df079f0 100644
--- a/jscomp/stdlib/stack.js
+++ b/jscomp/stdlib/stack.js
@@ -1,15 +1,10 @@
 // Generated CODE, PLEASE EDIT WITH CARE
 'use strict';
 
-var Caml_builtin_exceptions = require("../runtime/caml_builtin_exceptions");
-var List                    = require("./list");
+var Caml_exceptions = require("../runtime/caml_exceptions");
+var List            = require("./list");
 
-var Empty = {
-  0: "Stack.Empty",
-  1: Caml_builtin_exceptions.get_id(),
-  length: 2,
-  tag: 248
-};
+var Empty = Caml_exceptions.create("Stack.Empty");
 
 function create() {
   return /* record */[/* [] */0];
diff --git a/jscomp/stdlib/stream.js b/jscomp/stdlib/stream.js
index 4278baac07..1893143372 100644
--- a/jscomp/stdlib/stream.js
+++ b/jscomp/stdlib/stream.js
@@ -3,23 +3,14 @@
 
 var Caml_builtin_exceptions = require("../runtime/caml_builtin_exceptions");
 var CamlinternalLazy        = require("./camlinternalLazy");
+var Caml_exceptions         = require("../runtime/caml_exceptions");
 var Pervasives              = require("./pervasives");
 var Caml_curry              = require("../runtime/caml_curry");
 var List                    = require("./list");
 
-var Failure = {
-  0: "Stream.Failure",
-  1: Caml_builtin_exceptions.get_id(),
-  length: 2,
-  tag: 248
-};
+var Failure = Caml_exceptions.create("Stream.Failure");
 
-var $$Error = {
-  0: "Stream.Error",
-  1: Caml_builtin_exceptions.get_id(),
-  length: 2,
-  tag: 248
-};
+var $$Error = Caml_exceptions.create("Stream.Error");
 
 function fill_buff(b) {
   b[/* len */2] = Pervasives.input(b[/* ic */0], b[/* buff */1], 0, b[/* buff */1].length);
diff --git a/jscomp/stdlib/sys.js b/jscomp/stdlib/sys.js
index f0174402d3..98ba66f521 100644
--- a/jscomp/stdlib/sys.js
+++ b/jscomp/stdlib/sys.js
@@ -1,7 +1,7 @@
 // Generated CODE, PLEASE EDIT WITH CARE
 'use strict';
 
-var Caml_builtin_exceptions = require("../runtime/caml_builtin_exceptions");
+var Caml_exceptions = require("../runtime/caml_exceptions");
 
 var is_js = /* true */1;
 
@@ -28,12 +28,7 @@ function set_signal(sig_num, sig_beh) {
   return sig_beh;
 }
 
-var Break = {
-  0: "Sys.Break",
-  1: Caml_builtin_exceptions.get_id(),
-  length: 2,
-  tag: 248
-};
+var Break = Caml_exceptions.create("Sys.Break");
 
 function catch_break(on) {
   if (on) {
diff --git a/jscomp/stdlib/unix.js b/jscomp/stdlib/unix.js
index ad2b121965..c0d33a17cf 100644
--- a/jscomp/stdlib/unix.js
+++ b/jscomp/stdlib/unix.js
@@ -4,6 +4,7 @@
 var Caml_builtin_exceptions = require("../runtime/caml_builtin_exceptions");
 var Caml_io                 = require("../runtime/caml_io");
 var Caml_sys                = require("../runtime/caml_sys");
+var Caml_exceptions         = require("../runtime/caml_exceptions");
 var Pervasives              = require("./pervasives");
 var Hashtbl                 = require("./hashtbl");
 var Caml_format             = require("../runtime/caml_format");
@@ -18,12 +19,7 @@ var Caml_curry              = require("../runtime/caml_curry");
 var Caml_string             = require("../runtime/caml_string");
 var List                    = require("./list");
 
-var Unix_error = {
-  0: "Unix.Unix_error",
-  1: Caml_builtin_exceptions.get_id(),
-  length: 2,
-  tag: 248
-};
+var Unix_error = Caml_exceptions.create("Unix.Unix_error");
 
 Callback.register_exception("Unix.Unix_error", [
       Unix_error,
diff --git a/jscomp/test/.depend b/jscomp/test/.depend
index 7546423c4f..c0d716f0d1 100644
--- a/jscomp/test/.depend
+++ b/jscomp/test/.depend
@@ -132,6 +132,8 @@ event_ffi.cmo : ../lib/js.cmo ../lib/fn.cmo
 event_ffi.cmx : ../lib/js.cmx ../lib/fn.cmx
 exception_raise_test.cmo : mt.cmi
 exception_raise_test.cmx : mt.cmx
+exception_value_test.cmo :
+exception_value_test.cmx :
 ext_array.cmo : ../stdlib/list.cmi ../stdlib/array.cmi
 ext_array.cmx : ../stdlib/list.cmx ../stdlib/array.cmx
 ext_bytes.cmo : ../stdlib/bytes.cmi
@@ -682,6 +684,8 @@ event_ffi.cmo : ../lib/js.cmo ../lib/fn.cmo
 event_ffi.cmj : ../lib/js.cmj ../lib/fn.cmj
 exception_raise_test.cmo : mt.cmi
 exception_raise_test.cmj : mt.cmj
+exception_value_test.cmo :
+exception_value_test.cmj :
 ext_array.cmo : ../stdlib/list.cmi ../stdlib/array.cmi
 ext_array.cmj : ../stdlib/list.cmj ../stdlib/array.cmj
 ext_bytes.cmo : ../stdlib/bytes.cmi
diff --git a/jscomp/test/class6_test.js b/jscomp/test/class6_test.js
index b79e186231..6c26ba307f 100644
--- a/jscomp/test/class6_test.js
+++ b/jscomp/test/class6_test.js
@@ -3,6 +3,7 @@
 
 var Caml_obj                = require("../runtime/caml_obj");
 var Caml_builtin_exceptions = require("../runtime/caml_builtin_exceptions");
+var Caml_exceptions         = require("../runtime/caml_exceptions");
 var Mt                      = require("./mt");
 var CamlinternalOO          = require("../stdlib/camlinternalOO");
 var Caml_curry              = require("../runtime/caml_curry");
@@ -203,7 +204,7 @@ function functional_point_init($$class) {
         },
         move,
         function (self$neg6, d) {
-          var copy = Caml_builtin_exceptions.caml_set_oo_id(Caml_obj.caml_obj_dup(self$neg6));
+          var copy = Caml_exceptions.caml_set_oo_id(Caml_obj.caml_obj_dup(self$neg6));
           copy[x] = self$neg6[x] + d | 0;
           return copy;
         }
diff --git a/jscomp/test/class7_test.js b/jscomp/test/class7_test.js
index 45c1f503fa..32e9a59473 100644
--- a/jscomp/test/class7_test.js
+++ b/jscomp/test/class7_test.js
@@ -1,12 +1,12 @@
 // Generated CODE, PLEASE EDIT WITH CARE
 'use strict';
 
-var Caml_builtin_exceptions = require("../runtime/caml_builtin_exceptions");
-var Caml_obj                = require("../runtime/caml_obj");
-var Mt                      = require("./mt");
-var CamlinternalOO          = require("../stdlib/camlinternalOO");
-var Caml_curry              = require("../runtime/caml_curry");
-var Oo                      = require("../stdlib/oo");
+var Caml_obj        = require("../runtime/caml_obj");
+var Caml_exceptions = require("../runtime/caml_exceptions");
+var Mt              = require("./mt");
+var CamlinternalOO  = require("../stdlib/camlinternalOO");
+var Caml_curry      = require("../runtime/caml_curry");
+var Oo              = require("../stdlib/oo");
 
 var shared = ["copy"];
 
@@ -134,7 +134,7 @@ function backup_init($$class) {
   CamlinternalOO.set_methods($$class, /* array */[
         save,
         function (self$neg3) {
-          var copy$1 = Caml_builtin_exceptions.caml_set_oo_id(Caml_obj.caml_obj_dup(self$neg3));
+          var copy$1 = Caml_exceptions.caml_set_oo_id(Caml_obj.caml_obj_dup(self$neg3));
           self$neg3[copy] = /* Some */[(copy$1[copy] = /* None */0, copy$1)];
           return /* () */0;
         },
@@ -257,7 +257,7 @@ function backup2_init($$class) {
   CamlinternalOO.set_methods($$class, /* array */[
         save,
         function (self$neg5) {
-          self$neg5[copy] = /* Some */[Caml_builtin_exceptions.caml_set_oo_id(Caml_obj.caml_obj_dup(self$neg5))];
+          self$neg5[copy] = /* Some */[Caml_exceptions.caml_set_oo_id(Caml_obj.caml_obj_dup(self$neg5))];
           return /* () */0;
         },
         restore,
diff --git a/jscomp/test/class8_test.js b/jscomp/test/class8_test.js
index ada747793f..8c6600dfa4 100644
--- a/jscomp/test/class8_test.js
+++ b/jscomp/test/class8_test.js
@@ -1,11 +1,11 @@
 // Generated CODE, PLEASE EDIT WITH CARE
 'use strict';
 
-var Caml_obj                = require("../runtime/caml_obj");
-var Caml_builtin_exceptions = require("../runtime/caml_builtin_exceptions");
-var Mt                      = require("./mt");
-var CamlinternalOO          = require("../stdlib/camlinternalOO");
-var Caml_curry              = require("../runtime/caml_curry");
+var Caml_obj        = require("../runtime/caml_obj");
+var Caml_exceptions = require("../runtime/caml_exceptions");
+var Mt              = require("./mt");
+var CamlinternalOO  = require("../stdlib/camlinternalOO");
+var Caml_curry      = require("../runtime/caml_curry");
 
 var shared = [
   "leq",
@@ -91,7 +91,7 @@ function money2_init($$class) {
   var obj_init = inh[0];
   var repr = inh[1];
   CamlinternalOO.set_method($$class, times, function (self$neg3, k) {
-        var copy = Caml_builtin_exceptions.caml_set_oo_id(Caml_obj.caml_obj_dup(self$neg3));
+        var copy = Caml_exceptions.caml_set_oo_id(Caml_obj.caml_obj_dup(self$neg3));
         copy[repr] = k * self$neg3[repr];
         return copy;
       });
diff --git a/jscomp/test/equal_exception_test.js b/jscomp/test/equal_exception_test.js
index a606987421..617dc538ce 100644
--- a/jscomp/test/equal_exception_test.js
+++ b/jscomp/test/equal_exception_test.js
@@ -3,6 +3,7 @@
 
 var Bytes                   = require("../stdlib/bytes");
 var Caml_builtin_exceptions = require("../runtime/caml_builtin_exceptions");
+var Caml_exceptions         = require("../runtime/caml_exceptions");
 var Mt                      = require("./mt");
 
 var v = "gso";
@@ -70,12 +71,7 @@ function is_exception() {
 }
 
 function is_normal_exception() {
-  var A = {
-    0: "A",
-    1: Caml_builtin_exceptions.get_id(),
-    length: 2,
-    tag: 248
-  };
+  var A = Caml_exceptions.create("A");
   var v = [
     A,
     3
@@ -99,12 +95,7 @@ function is_normal_exception() {
 }
 
 function is_arbitrary_exception() {
-  var A = {
-    0: "A",
-    1: Caml_builtin_exceptions.get_id(),
-    length: 2,
-    tag: 248
-  };
+  var A = Caml_exceptions.create("A");
   try {
     throw A;
   }
diff --git a/jscomp/test/exception_raise_test.js b/jscomp/test/exception_raise_test.js
index 558a8b96b9..6e189e37dd 100644
--- a/jscomp/test/exception_raise_test.js
+++ b/jscomp/test/exception_raise_test.js
@@ -2,44 +2,20 @@
 'use strict';
 
 var Caml_builtin_exceptions = require("../runtime/caml_builtin_exceptions");
+var Caml_exceptions         = require("../runtime/caml_exceptions");
 var Mt                      = require("./mt");
 var Caml_curry              = require("../runtime/caml_curry");
 
-var Local = {
-  0: "Exception_raise_test.Local",
-  1: Caml_builtin_exceptions.get_id(),
-  length: 2,
-  tag: 248
-};
+var Local = Caml_exceptions.create("Exception_raise_test.Local");
 
-var B = {
-  0: "Exception_raise_test.B",
-  1: Caml_builtin_exceptions.get_id(),
-  length: 2,
-  tag: 248
-};
+var B = Caml_exceptions.create("Exception_raise_test.B");
 
-var C = {
-  0: "Exception_raise_test.C",
-  1: Caml_builtin_exceptions.get_id(),
-  length: 2,
-  tag: 248
-};
+var C = Caml_exceptions.create("Exception_raise_test.C");
 
-var D = {
-  0: "Exception_raise_test.D",
-  1: Caml_builtin_exceptions.get_id(),
-  length: 2,
-  tag: 248
-};
+var D = Caml_exceptions.create("Exception_raise_test.D");
 
 function appf(g, x) {
-  var A = {
-    0: "A",
-    1: Caml_builtin_exceptions.get_id(),
-    length: 2,
-    tag: 248
-  };
+  var A = Caml_exceptions.create("A");
   try {
     return Caml_curry.app1(g, x);
   }
@@ -93,12 +69,7 @@ function appf(g, x) {
   }
 }
 
-var A = {
-  0: "Exception_raise_test.A",
-  1: Caml_builtin_exceptions.get_id(),
-  length: 2,
-  tag: 248
-};
+var A = Caml_exceptions.create("Exception_raise_test.A");
 
 var f;
 
diff --git a/jscomp/test/exception_value_test.js b/jscomp/test/exception_value_test.js
new file mode 100644
index 0000000000..d26e5e1ce0
--- /dev/null
+++ b/jscomp/test/exception_value_test.js
@@ -0,0 +1,31 @@
+// Generated CODE, PLEASE EDIT WITH CARE
+'use strict';
+
+var Caml_builtin_exceptions = require("../runtime/caml_builtin_exceptions");
+
+function f() {
+  throw Caml_builtin_exceptions.not_found;
+}
+
+function assert_f(x) {
+  if (x <= 3) {
+    throw [
+          Caml_builtin_exceptions.assert_failure,
+          [
+            "exception_value_test.ml",
+            9,
+            12
+          ]
+        ];
+  }
+  return 3;
+}
+
+function hh() {
+  throw Caml_builtin_exceptions.not_found;
+}
+
+exports.f        = f;
+exports.assert_f = assert_f;
+exports.hh       = hh;
+/* No side effect */
diff --git a/jscomp/test/exception_value_test.ml b/jscomp/test/exception_value_test.ml
new file mode 100644
index 0000000000..4fd6d30d9b
--- /dev/null
+++ b/jscomp/test/exception_value_test.ml
@@ -0,0 +1,16 @@
+
+
+let f () =
+  raise  Not_found
+
+
+
+let assert_f x = 
+  let ()  = assert (x > 3) in 
+  3 
+
+
+let hh () = 
+  let v = raise Not_found in 
+  v + 3 
+ (* TODO: comment for line column number *)
diff --git a/jscomp/test/ext_string.js b/jscomp/test/ext_string.js
index 96ca21da7d..60c89c4c67 100644
--- a/jscomp/test/ext_string.js
+++ b/jscomp/test/ext_string.js
@@ -3,6 +3,7 @@
 
 var Bytes                   = require("../stdlib/bytes");
 var Caml_builtin_exceptions = require("../runtime/caml_builtin_exceptions");
+var Caml_exceptions         = require("../runtime/caml_exceptions");
 var Caml_primitive          = require("../runtime/caml_primitive");
 var Ext_bytes               = require("./ext_bytes");
 var $$String                = require("../stdlib/string");
@@ -214,12 +215,7 @@ function find($staropt$star, sub, s) {
   var start = $staropt$star ? $staropt$star[0] : 0;
   var n = sub.length;
   var i = start;
-  var Exit = {
-    0: "Exit",
-    1: Caml_builtin_exceptions.get_id(),
-    length: 2,
-    tag: 248
-  };
+  var Exit = Caml_exceptions.create("Exit");
   try {
     while((i + n | 0) <= s.length) {
       if (_is_sub(sub, 0, s, i, n)) {
@@ -242,12 +238,7 @@ function find($staropt$star, sub, s) {
 function rfind(sub, s) {
   var n = sub.length;
   var i = s.length - n | 0;
-  var Exit = {
-    0: "Exit",
-    1: Caml_builtin_exceptions.get_id(),
-    length: 2,
-    tag: 248
-  };
+  var Exit = Caml_exceptions.create("Exit");
   try {
     while(i >= 0) {
       if (_is_sub(sub, 0, s, i, n)) {
diff --git a/jscomp/test/extensible_variant_test.js b/jscomp/test/extensible_variant_test.js
index bdf04482ec..ac073ce5eb 100644
--- a/jscomp/test/extensible_variant_test.js
+++ b/jscomp/test/extensible_variant_test.js
@@ -2,30 +2,16 @@
 'use strict';
 
 var Caml_builtin_exceptions = require("../runtime/caml_builtin_exceptions");
+var Caml_exceptions         = require("../runtime/caml_exceptions");
 var Mt                      = require("./mt");
 
-var Str = {
-  0: "Extensible_variant_test.Str",
-  1: Caml_builtin_exceptions.get_id(),
-  length: 2,
-  tag: 248
-};
+var Str = Caml_exceptions.create("Extensible_variant_test.Str");
 
-var Int = {
-  0: "Extensible_variant_test.N.Int",
-  1: Caml_builtin_exceptions.get_id(),
-  length: 2,
-  tag: 248
-};
+var Int = Caml_exceptions.create("Extensible_variant_test.N.Int");
 
 var N = /* module */[Int];
 
-var Int$1 = {
-  0: "Extensible_variant_test.Int",
-  1: Caml_builtin_exceptions.get_id(),
-  length: 2,
-  tag: 248
-};
+var Int$1 = Caml_exceptions.create("Extensible_variant_test.Int");
 
 function to_int(x) {
   if (x[0] === Str) {
diff --git a/jscomp/test/local_exception_test.js b/jscomp/test/local_exception_test.js
index 152c567544..1724d1ae4b 100644
--- a/jscomp/test/local_exception_test.js
+++ b/jscomp/test/local_exception_test.js
@@ -1,14 +1,9 @@
 // Generated CODE, PLEASE EDIT WITH CARE
 'use strict';
 
-var Caml_builtin_exceptions = require("../runtime/caml_builtin_exceptions");
+var Caml_exceptions = require("../runtime/caml_exceptions");
 
-var A = {
-  0: "Local_exception_test.A",
-  1: Caml_builtin_exceptions.get_id(),
-  length: 2,
-  tag: 248
-};
+var A = Caml_exceptions.create("Local_exception_test.A");
 
 var v = [
   A,
@@ -16,31 +11,16 @@ var v = [
   /* true */1
 ];
 
-var B = {
-  0: "Local_exception_test.B",
-  1: Caml_builtin_exceptions.get_id(),
-  length: 2,
-  tag: 248
-};
+var B = Caml_exceptions.create("Local_exception_test.B");
 
-var D = {
-  0: "Local_exception_test.D",
-  1: Caml_builtin_exceptions.get_id(),
-  length: 2,
-  tag: 248
-};
+var D = Caml_exceptions.create("Local_exception_test.D");
 
 var d = [
   D,
   3
 ];
 
-var A$1 = {
-  0: "Local_exception_test.A",
-  1: Caml_builtin_exceptions.get_id(),
-  length: 2,
-  tag: 248
-};
+var A$1 = Caml_exceptions.create("Local_exception_test.A");
 
 var x = [
   A$1,
diff --git a/jscomp/test/pq_test.js b/jscomp/test/pq_test.js
index bb2d596cbd..50c41d2d91 100644
--- a/jscomp/test/pq_test.js
+++ b/jscomp/test/pq_test.js
@@ -1,7 +1,7 @@
 // Generated CODE, PLEASE EDIT WITH CARE
 'use strict';
 
-var Caml_builtin_exceptions = require("../runtime/caml_builtin_exceptions");
+var Caml_exceptions = require("../runtime/caml_exceptions");
 
 function insert(queue, prio, elt) {
   if (queue) {
@@ -36,12 +36,7 @@ function insert(queue, prio, elt) {
   }
 }
 
-var Queue_is_empty = {
-  0: "Pq_test.PrioQueue.Queue_is_empty",
-  1: Caml_builtin_exceptions.get_id(),
-  length: 2,
-  tag: 248
-};
+var Queue_is_empty = Caml_exceptions.create("Pq_test.PrioQueue.Queue_is_empty");
 
 function remove_top(param) {
   if (param) {
diff --git a/jscomp/test/test.mllib b/jscomp/test/test.mllib
index ca4343b1a8..d52ba92d4d 100644
--- a/jscomp/test/test.mllib
+++ b/jscomp/test/test.mllib
@@ -242,9 +242,10 @@ class7_test
 class8_test
 class_repr
 
-
+pq_test
 mt_global
 
 event_ffi
 
-hash_test
\ No newline at end of file
+hash_test
+exception_value_test
\ No newline at end of file
diff --git a/jscomp/test/test_common.js b/jscomp/test/test_common.js
index 6d5220a243..1231e95e09 100644
--- a/jscomp/test/test_common.js
+++ b/jscomp/test/test_common.js
@@ -1,21 +1,11 @@
 // Generated CODE, PLEASE EDIT WITH CARE
 'use strict';
 
-var Caml_builtin_exceptions = require("../runtime/caml_builtin_exceptions");
+var Caml_exceptions = require("../runtime/caml_exceptions");
 
-var U = {
-  0: "Test_common.U",
-  1: Caml_builtin_exceptions.get_id(),
-  length: 2,
-  tag: 248
-};
+var U = Caml_exceptions.create("Test_common.U");
 
-var H = {
-  0: "Test_common.H",
-  1: Caml_builtin_exceptions.get_id(),
-  length: 2,
-  tag: 248
-};
+var H = Caml_exceptions.create("Test_common.H");
 
 exports.U = U;
 exports.H = H;
diff --git a/jscomp/test/test_exception.js b/jscomp/test/test_exception.js
index 532a729d22..caccaff5a6 100644
--- a/jscomp/test/test_exception.js
+++ b/jscomp/test/test_exception.js
@@ -2,14 +2,10 @@
 'use strict';
 
 var Caml_builtin_exceptions = require("../runtime/caml_builtin_exceptions");
+var Caml_exceptions         = require("../runtime/caml_exceptions");
 var Test_common             = require("./test_common");
 
-var Local = {
-  0: "Test_exception.Local",
-  1: Caml_builtin_exceptions.get_id(),
-  length: 2,
-  tag: 248
-};
+var Local = Caml_exceptions.create("Test_exception.Local");
 
 function f() {
   throw [
diff --git a/jscomp/test/test_exception_escape.js b/jscomp/test/test_exception_escape.js
index 139a1fff26..1bbea3056d 100644
--- a/jscomp/test/test_exception_escape.js
+++ b/jscomp/test/test_exception_escape.js
@@ -1,14 +1,9 @@
 // Generated CODE, PLEASE EDIT WITH CARE
 'use strict';
 
-var Caml_builtin_exceptions = require("../runtime/caml_builtin_exceptions");
+var Caml_exceptions = require("../runtime/caml_exceptions");
 
-var A = {
-  0: "Test_exception_escape.N.A",
-  1: Caml_builtin_exceptions.get_id(),
-  length: 2,
-  tag: 248
-};
+var A = Caml_exceptions.create("Test_exception_escape.N.A");
 
 var f;
 
diff --git a/jscomp/test/test_internalOO.js b/jscomp/test/test_internalOO.js
index 72c02f09fe..80ff4aace5 100644
--- a/jscomp/test/test_internalOO.js
+++ b/jscomp/test/test_internalOO.js
@@ -1,9 +1,10 @@
 // Generated CODE, PLEASE EDIT WITH CARE
 'use strict';
 
-var Caml_builtin_exceptions = require("../runtime/caml_builtin_exceptions");
 var Caml_obj                = require("../runtime/caml_obj");
+var Caml_builtin_exceptions = require("../runtime/caml_builtin_exceptions");
 var Obj                     = require("../stdlib/obj");
+var Caml_exceptions         = require("../runtime/caml_exceptions");
 var Caml_oo                 = require("../runtime/caml_oo");
 var Sys                     = require("../stdlib/sys");
 var Caml_primitive          = require("../runtime/caml_primitive");
@@ -14,7 +15,7 @@ var Caml_string             = require("../runtime/caml_string");
 var List                    = require("../stdlib/list");
 
 function copy(o) {
-  return Caml_builtin_exceptions.caml_set_oo_id(Caml_obj.caml_obj_dup(o));
+  return Caml_exceptions.caml_set_oo_id(Caml_obj.caml_obj_dup(o));
 }
 
 var params = /* record */[
@@ -2690,7 +2691,7 @@ function create_object(table) {
     tag: Obj.object_tag
   };
   obj[0] = table[/* methods */1];
-  return Caml_builtin_exceptions.caml_set_oo_id(obj);
+  return Caml_exceptions.caml_set_oo_id(obj);
 }
 
 function create_object_opt(obj_0, table) {
@@ -2703,7 +2704,7 @@ function create_object_opt(obj_0, table) {
       tag: Obj.object_tag
     };
     obj[0] = table[/* methods */1];
-    return Caml_builtin_exceptions.caml_set_oo_id(obj);
+    return Caml_exceptions.caml_set_oo_id(obj);
   }
 }
 
diff --git a/jscomp/test/test_literal.js b/jscomp/test/test_literal.js
index c080a757b3..aab367534d 100644
--- a/jscomp/test/test_literal.js
+++ b/jscomp/test/test_literal.js
@@ -1,14 +1,9 @@
 // Generated CODE, PLEASE EDIT WITH CARE
 'use strict';
 
-var Caml_builtin_exceptions = require("../runtime/caml_builtin_exceptions");
-
-var Custom_inline = {
-  0: "Test_literal.Custom_inline",
-  1: Caml_builtin_exceptions.get_id(),
-  length: 2,
-  tag: 248
-};
+var Caml_exceptions = require("../runtime/caml_exceptions");
+
+var Custom_inline = Caml_exceptions.create("Test_literal.Custom_inline");
 
 var v = [
   Custom_inline,
diff --git a/jscomp/test/test_per.js b/jscomp/test/test_per.js
index f0ae19a588..8da7a1836d 100644
--- a/jscomp/test/test_per.js
+++ b/jscomp/test/test_per.js
@@ -4,6 +4,7 @@
 var Caml_builtin_exceptions  = require("../runtime/caml_builtin_exceptions");
 var Caml_obj                 = require("../runtime/caml_obj");
 var Caml_io                  = require("../runtime/caml_io");
+var Caml_exceptions          = require("../runtime/caml_exceptions");
 var Caml_format              = require("../runtime/caml_format");
 var Caml_primitive           = require("../runtime/caml_primitive");
 var CamlinternalFormatBasics = require("../stdlib/camlinternalFormatBasics");
@@ -24,12 +25,7 @@ function invalid_arg(s) {
       ];
 }
 
-var Exit = {
-  0: "Test_per.Exit",
-  1: Caml_builtin_exceptions.get_id(),
-  length: 2,
-  tag: 248
-};
+var Exit = Caml_exceptions.create("Test_per.Exit");
 
 function min(x, y) {
   if (Caml_obj.caml_lessequal(x, y)) {
diff --git a/jscomp/test/test_seq.js b/jscomp/test/test_seq.js
index 8b545802aa..a9925977d6 100644
--- a/jscomp/test/test_seq.js
+++ b/jscomp/test/test_seq.js
@@ -1,31 +1,17 @@
 // Generated CODE, PLEASE EDIT WITH CARE
 'use strict';
 
-var Caml_builtin_exceptions = require("../runtime/caml_builtin_exceptions");
 var Caml_obj                = require("../runtime/caml_obj");
+var Caml_builtin_exceptions = require("../runtime/caml_builtin_exceptions");
+var Caml_exceptions         = require("../runtime/caml_exceptions");
 var Pervasives              = require("../stdlib/pervasives");
 var Caml_curry              = require("../runtime/caml_curry");
 
-var Bad = {
-  0: "Test_seq.Bad",
-  1: Caml_builtin_exceptions.get_id(),
-  length: 2,
-  tag: 248
-};
+var Bad = Caml_exceptions.create("Test_seq.Bad");
 
-var Help = {
-  0: "Test_seq.Help",
-  1: Caml_builtin_exceptions.get_id(),
-  length: 2,
-  tag: 248
-};
+var Help = Caml_exceptions.create("Test_seq.Help");
 
-var Stop = {
-  0: "Test_seq.Stop",
-  1: Caml_builtin_exceptions.get_id(),
-  length: 2,
-  tag: 248
-};
+var Stop = Caml_exceptions.create("Test_seq.Stop");
 
 function assoc3(x, _l) {
   while(true) {
diff --git a/jscomp/test/test_static_catch_ident.js b/jscomp/test/test_static_catch_ident.js
index 313fc9deff..d91caa9bf5 100644
--- a/jscomp/test/test_static_catch_ident.js
+++ b/jscomp/test/test_static_catch_ident.js
@@ -2,13 +2,9 @@
 'use strict';
 
 var Caml_builtin_exceptions = require("../runtime/caml_builtin_exceptions");
+var Caml_exceptions         = require("../runtime/caml_exceptions");
 
-var Scan_failure = {
-  0: "Test_static_catch_ident.Scan_failure",
-  1: Caml_builtin_exceptions.get_id(),
-  length: 2,
-  tag: 248
-};
+var Scan_failure = Caml_exceptions.create("Test_static_catch_ident.Scan_failure");
 
 function scanf_bad_input(_, x) {
   var exit = 0;