diff --git a/jscomp/js_config.ml b/jscomp/js_config.ml
index 97f0cb5ef7..8e933328d7 100644
--- a/jscomp/js_config.ml
+++ b/jscomp/js_config.ml
@@ -171,4 +171,4 @@ let bigarray = "Caml_bigarray"
 let unix = "Caml_unix"
 let int64 = "Caml_int64"
 let md5 = "Caml_md5"
-
+let weak = "Caml_weak"
diff --git a/jscomp/js_config.mli b/jscomp/js_config.mli
index 64113cdbfa..8e455ac62a 100644
--- a/jscomp/js_config.mli
+++ b/jscomp/js_config.mli
@@ -65,3 +65,4 @@ val unix : string
 val int64 : string
 val md5 : string
 val hash : string
+val weak : string
diff --git a/jscomp/lam_dispatch_primitive.ml b/jscomp/lam_dispatch_primitive.ml
index e15e4b4122..9a8f383aca 100644
--- a/jscomp/lam_dispatch_primitive.ml
+++ b/jscomp/lam_dispatch_primitive.ml
@@ -793,7 +793,13 @@ let query (prim : Lam_compile_env.primitive_description)
     -> E.runtime_call Js_config.md5 prim.prim_name args
   | "caml_hash"
     -> E.runtime_call Js_config.hash prim.prim_name args
-
+  | "caml_weak_set"
+  | "caml_weak_create"
+  | "caml_weak_get"
+  | "caml_weak_check"
+  | "caml_weak_blit"
+  | "caml_weak_get_copy"
+    -> E.runtime_call Js_config.weak prim.prim_name args
   | "caml_output_value_to_buffer"
   | "caml_marshal_data_size"
   | "caml_input_value_from_string"
@@ -804,12 +810,6 @@ let query (prim : Lam_compile_env.primitive_description)
   | "caml_md5_chan"
 
   | "caml_hash_univ_param"
-  | "caml_weak_set"
-  | "caml_weak_create"
-  | "caml_weak_get"
-  | "caml_weak_check"
-  | "caml_weak_blit"
-  | "caml_weak_get_copy"
   | "caml_sys_close"
 
   | "caml_sys_open"
diff --git a/jscomp/runtime/.depend b/jscomp/runtime/.depend
index 70b3df2c7e..88f06f74a0 100644
--- a/jscomp/runtime/.depend
+++ b/jscomp/runtime/.depend
@@ -15,6 +15,7 @@ caml_queue.cmi :
 caml_string.cmi :
 caml_sys.cmi :
 caml_utils.cmi :
+caml_weak.cmi :
 caml_array.cmo : js.cmo caml_array.cmi
 caml_array.cmx : js.cmx caml_array.cmi
 caml_bigarray.cmo : caml_bigarray.cmi
@@ -53,6 +54,8 @@ caml_sys.cmo : js.cmo caml_sys.cmi
 caml_sys.cmx : js.cmx caml_sys.cmi
 caml_utils.cmo : caml_utils.cmi
 caml_utils.cmx : caml_utils.cmi
+caml_weak.cmo : caml_array.cmi caml_weak.cmi
+caml_weak.cmx : caml_array.cmx caml_weak.cmi
 fn.cmo :
 fn.cmx :
 js.cmo :
@@ -99,6 +102,8 @@ caml_sys.cmo : js.cmo caml_sys.cmi
 caml_sys.cmj : js.cmj caml_sys.cmi
 caml_utils.cmo : caml_utils.cmi
 caml_utils.cmj : caml_utils.cmi
+caml_weak.cmo : caml_array.cmi caml_weak.cmi
+caml_weak.cmj : caml_array.cmj caml_weak.cmi
 fn.cmo :
 fn.cmj :
 js.cmo :
diff --git a/jscomp/runtime/runtime.mllib b/jscomp/runtime/runtime.mllib
index 0deb9a5aa1..b901a85033 100644
--- a/jscomp/runtime/runtime.mllib
+++ b/jscomp/runtime/runtime.mllib
@@ -17,6 +17,7 @@ caml_bigarray
 caml_md5
 caml_queue
 caml_hash
+caml_weak
 typed_array
 js
 fn
diff --git a/jscomp/stdlib/weak.js b/jscomp/stdlib/weak.js
index 3dfb33a603..e5496d3862 100644
--- a/jscomp/stdlib/weak.js
+++ b/jscomp/stdlib/weak.js
@@ -8,6 +8,7 @@ var Sys                     = require("./sys");
 var Caml_primitive          = require("../runtime/caml_primitive");
 var Caml_array              = require("../runtime/caml_array");
 var $$Array                 = require("./array");
+var Caml_weak               = require("../runtime/caml_weak");
 var Caml_curry              = require("../runtime/caml_curry");
 
 function length(x) {
@@ -23,14 +24,14 @@ function fill(ar, ofs, len, x) {
   }
   else {
     for(var i = ofs ,i_finish = (ofs + len | 0) - 1 | 0; i<= i_finish; ++i){
-      Caml_primitive.caml_weak_set(ar, i, x);
+      Caml_weak.caml_weak_set(ar, i, x);
     }
     return /* () */0;
   }
 }
 
 function Make(H) {
-  var emptybucket = Caml_primitive.caml_weak_create(0);
+  var emptybucket = Caml_weak.caml_weak_create(0);
   var get_index = function (t, h) {
     return (h & Pervasives.max_int) % t[/* table */0].length;
   };
@@ -66,7 +67,7 @@ function Make(H) {
                     return accu;
                   }
                   else {
-                    var match = Caml_primitive.caml_weak_get(b, i);
+                    var match = Caml_weak.caml_weak_get(b, i);
                     if (match) {
                       _accu = Caml_curry.app2(f, match[0], accu);
                       _i = i + 1 | 0;
@@ -92,7 +93,7 @@ function Make(H) {
                     return /* () */0;
                   }
                   else {
-                    var match = Caml_primitive.caml_weak_get(b, i);
+                    var match = Caml_weak.caml_weak_get(b, i);
                     if (match) {
                       Caml_curry.app1(f, match[0]);
                       _i = i + 1 | 0;
@@ -119,7 +120,7 @@ function Make(H) {
                     return /* () */0;
                   }
                   else {
-                    var match = Caml_primitive.caml_weak_check(b, i);
+                    var match = Caml_weak.caml_weak_check(b, i);
                     if (match !== 0) {
                       Caml_curry.app3(f, b, t[/* hashes */1][j], i);
                       _i = i + 1 | 0;
@@ -144,7 +145,7 @@ function Make(H) {
       }
       else {
         _accu = accu + (
-          Caml_primitive.caml_weak_check(b, i) ? 1 : 0
+          Caml_weak.caml_weak_check(b, i) ? 1 : 0
         ) | 0;
         _i = i + 1 | 0;
         continue ;
@@ -175,13 +176,13 @@ function Make(H) {
           var j = _j;
           var i = _i;
           if (j >= prev_len) {
-            if (Caml_primitive.caml_weak_check(bucket, i)) {
+            if (Caml_weak.caml_weak_check(bucket, i)) {
               _i = i + 1 | 0;
               continue ;
               
             }
-            else if (Caml_primitive.caml_weak_check(bucket, j)) {
-              Caml_primitive.caml_weak_blit(bucket, j, bucket, i, 1);
+            else if (Caml_weak.caml_weak_check(bucket, j)) {
+              Caml_weak.caml_weak_blit(bucket, j, bucket, i, 1);
               hbucket[i] = hbucket[j];
               _j = j - 1 | 0;
               _i = i + 1 | 0;
@@ -231,9 +232,9 @@ function Make(H) {
                 "Weak.Make: hash bucket cannot grow more"
               ];
         }
-        var newbucket = Caml_primitive.caml_weak_create(newsz);
+        var newbucket = Caml_weak.caml_weak_create(newsz);
         var newhashes = Caml_array.caml_make_vect(newsz, 0);
-        Caml_primitive.caml_weak_blit(bucket, 0, newbucket, 0, sz);
+        Caml_weak.caml_weak_blit(bucket, 0, newbucket, 0, sz);
         $$Array.blit(hashes, 0, newhashes, 0, sz);
         Caml_curry.app3(setter, newbucket, sz, d);
         newhashes[sz] = h;
@@ -254,7 +255,7 @@ function Make(H) {
             var add_weak = (function(newt){
             return function (ob, oh, oi) {
               var setter = function (nb, ni, _) {
-                return Caml_primitive.caml_weak_blit(ob, oi, nb, ni, 1);
+                return Caml_weak.caml_weak_blit(ob, oi, nb, ni, 1);
               };
               var h = oh[oi];
               return add_aux(newt, setter, /* None */0, h, get_index(newt, h));
@@ -278,7 +279,7 @@ function Make(H) {
           return 0;
         }
       }
-      else if (Caml_primitive.caml_weak_check(bucket, i)) {
+      else if (Caml_weak.caml_weak_check(bucket, i)) {
         _i = i + 1 | 0;
         continue ;
         
@@ -292,7 +293,7 @@ function Make(H) {
   };
   var add = function (t, d) {
     var h = Caml_curry.app1(H[1], d);
-    return add_aux(t, Caml_primitive.caml_weak_set, /* Some */[d], h, get_index(t, h));
+    return add_aux(t, Caml_weak.caml_weak_set, /* Some */[d], h, get_index(t, h));
   };
   var find_or = function (t, d, ifnotfound) {
     var h = Caml_curry.app1(H[1], d);
@@ -307,10 +308,10 @@ function Make(H) {
         return Caml_curry.app2(ifnotfound, h, index);
       }
       else if (h === hashes[i]) {
-        var match = Caml_primitive.caml_weak_get_copy(bucket, i);
+        var match = Caml_weak.caml_weak_get_copy(bucket, i);
         if (match) {
           if (Caml_curry.app2(H[0], match[0], d)) {
-            var match$1 = Caml_primitive.caml_weak_get(bucket, i);
+            var match$1 = Caml_weak.caml_weak_get(bucket, i);
             if (match$1) {
               return match$1[0];
             }
@@ -341,7 +342,7 @@ function Make(H) {
   };
   var merge = function (t, d) {
     return find_or(t, d, function (h, index) {
-                add_aux(t, Caml_primitive.caml_weak_set, /* Some */[d], h, index);
+                add_aux(t, Caml_weak.caml_weak_set, /* Some */[d], h, index);
                 return d;
               });
   };
@@ -363,7 +364,7 @@ function Make(H) {
         return ifnotfound;
       }
       else if (h === hashes[i]) {
-        var match = Caml_primitive.caml_weak_get_copy(bucket, i);
+        var match = Caml_weak.caml_weak_get_copy(bucket, i);
         if (match) {
           if (Caml_curry.app2(H[0], match[0], d)) {
             return Caml_curry.app2(iffound, bucket, i);
@@ -389,7 +390,7 @@ function Make(H) {
   };
   var remove = function (t, d) {
     return find_shadow(t, d, function (w, i) {
-                return Caml_primitive.caml_weak_set(w, i, /* None */0);
+                return Caml_weak.caml_weak_set(w, i, /* None */0);
               }, /* () */0);
   };
   var mem = function (t, d) {
@@ -412,10 +413,10 @@ function Make(H) {
         return accu;
       }
       else if (h === hashes[i]) {
-        var match = Caml_primitive.caml_weak_get_copy(bucket, i);
+        var match = Caml_weak.caml_weak_get_copy(bucket, i);
         if (match) {
           if (Caml_curry.app2(H[0], match[0], d)) {
-            var match$1 = Caml_primitive.caml_weak_get(bucket, i);
+            var match$1 = Caml_weak.caml_weak_get(bucket, i);
             if (match$1) {
               _accu = /* :: */[
                 match$1[0],
@@ -482,17 +483,17 @@ function Make(H) {
         ];
 }
 
-var create = Caml_primitive.caml_weak_create
+var create = Caml_weak.caml_weak_create
 
-var set = Caml_primitive.caml_weak_set
+var set = Caml_weak.caml_weak_set
 
-var get = Caml_primitive.caml_weak_get
+var get = Caml_weak.caml_weak_get
 
-var get_copy = Caml_primitive.caml_weak_get_copy
+var get_copy = Caml_weak.caml_weak_get_copy
 
-var check = Caml_primitive.caml_weak_check
+var check = Caml_weak.caml_weak_check
 
-var blit = Caml_primitive.caml_weak_blit
+var blit = Caml_weak.caml_weak_blit
 
 exports.create   = create;
 exports.length   = length;