diff --git a/jscomp/others/belt_HashMap.ml b/jscomp/others/belt_HashMap.ml
index 789ac4e1cf..270b827344 100644
--- a/jscomp/others/belt_HashMap.ml
+++ b/jscomp/others/belt_HashMap.ml
@@ -41,7 +41,7 @@ let rec copyBucketReHash ~hash ~h_buckets ~ndata_tail old_bucket =
   match C.toOpt old_bucket with
   | None -> ()
   | Some cell ->
-      let nidx = (hash cell.N.key [@bs]) land (A.length h_buckets - 1) in
+      let nidx = (hash cell.N.key [@u]) land (A.length h_buckets - 1) in
       let v = C.return cell in
       (match C.toOpt (A.getUnsafe ndata_tail nidx) with
       | None -> A.setUnsafe h_buckets nidx v
@@ -70,7 +70,7 @@ let resize ~hash h =
     done)
 
 let rec replaceInBucket ~eq key info cell =
-  if eq cell.N.key key [@bs] then (
+  if eq cell.N.key key [@u] then (
     cell.N.value <- info;
     false)
   else
@@ -81,7 +81,7 @@ let rec replaceInBucket ~eq key info cell =
 let set0 h key value ~eq ~hash =
   let h_buckets = h.C.buckets in
   let buckets_len = A.length h_buckets in
-  let i = (hash key [@bs]) land (buckets_len - 1) in
+  let i = (hash key [@u]) land (buckets_len - 1) in
   let l = A.getUnsafe h_buckets i in
   (match C.toOpt l with
   | None ->
@@ -106,7 +106,7 @@ let rec removeInBucket h h_buckets i key prec bucket ~eq =
   | None -> ()
   | Some cell ->
       let cell_next = cell.N.next in
-      if eq cell.N.key key [@bs] then (
+      if eq cell.N.key key [@u] then (
         prec.N.next <- cell_next;
         h.C.size <- h.C.size - 1)
       else removeInBucket ~eq h h_buckets i key cell cell_next
@@ -114,14 +114,14 @@ let rec removeInBucket h h_buckets i key prec bucket ~eq =
 let remove h key =
   let h_buckets = h.C.buckets in
   let i =
-    ((Belt_Id.getHashInternal h.C.hash) key [@bs]) land (A.length h_buckets - 1)
+    ((Belt_Id.getHashInternal h.C.hash) key [@u]) land (A.length h_buckets - 1)
   in
   let bucket = A.getUnsafe h_buckets i in
   match C.toOpt bucket with
   | None -> ()
   | Some cell ->
       let eq = Belt_Id.getEqInternal h.C.eq in
-      if eq cell.N.key key [@bs] then (
+      if eq cell.N.key key [@u] then (
         A.setUnsafe h_buckets i cell.N.next;
         h.C.size <- h.C.size - 1)
       else removeInBucket ~eq h h_buckets i key cell cell.N.next
@@ -130,33 +130,33 @@ let rec getAux ~eq key buckets =
   match C.toOpt buckets with
   | None -> None
   | Some cell ->
-      if eq key cell.N.key [@bs] then Some cell.N.value
+      if eq key cell.N.key [@u] then Some cell.N.value
       else getAux ~eq key cell.N.next
 
 let get h key =
   let h_buckets = h.C.buckets in
   let nid =
-    ((Belt_Id.getHashInternal h.C.hash) key [@bs]) land (A.length h_buckets - 1)
+    ((Belt_Id.getHashInternal h.C.hash) key [@u]) land (A.length h_buckets - 1)
   in
   match C.toOpt (A.getUnsafe h_buckets nid) with
   | None -> None
   | Some (cell1 : _ N.bucket) -> (
       let eq = Belt_Id.getEqInternal h.C.eq in
-      if eq key cell1.key [@bs] then Some cell1.value
+      if eq key cell1.key [@u] then Some cell1.value
       else
         match C.toOpt cell1.N.next with
         | None -> None
         | Some cell2 -> (
-            if eq key cell2.key [@bs] then Some cell2.value
+            if eq key cell2.key [@u] then Some cell2.value
             else
               match C.toOpt cell2.next with
               | None -> None
               | Some cell3 ->
-                  if eq key cell3.key [@bs] then Some cell3.value
+                  if eq key cell3.key [@u] then Some cell3.value
                   else getAux ~eq key cell3.next))
 
 let rec memInBucket key cell ~eq =
-  (eq cell.N.key key [@bs])
+  (eq cell.N.key key [@u])
   ||
   match C.toOpt cell.N.next with
   | None -> false
@@ -165,7 +165,7 @@ let rec memInBucket key cell ~eq =
 let has h key =
   let h_buckets = h.C.buckets in
   let nid =
-    ((Belt_Id.getHashInternal h.C.hash) key [@bs]) land (A.length h_buckets - 1)
+    ((Belt_Id.getHashInternal h.C.hash) key [@u]) land (A.length h_buckets - 1)
   in
   let bucket = A.getUnsafe h_buckets nid in
   match C.toOpt bucket with
diff --git a/jscomp/others/belt_HashSet.ml b/jscomp/others/belt_HashSet.ml
index 5b5cf982ce..2192b7a2a1 100644
--- a/jscomp/others/belt_HashSet.ml
+++ b/jscomp/others/belt_HashSet.ml
@@ -1,5 +1,5 @@
 (* Copyright (C) 2017 Hongbo Zhang, Authors of ReScript
- * 
+ *
  * 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, either version 3 of the License, or
@@ -17,7 +17,7 @@
  * 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. *)
@@ -38,7 +38,7 @@ let rec copyBucket ~hash ~h_buckets ~ndata_tail old_bucket =
   | None -> ()
   | Some cell ->
       let nidx =
-        ((Belt_Id.getHashInternal hash) cell.N.key [@bs])
+        ((Belt_Id.getHashInternal hash) cell.N.key [@u])
         land (A.length h_buckets - 1)
       in
       let v = C.return cell in
@@ -70,7 +70,7 @@ let tryDoubleResize ~hash h =
 
 let rec removeBucket ~eq h h_buckets i key prec cell =
   let cell_next = cell.N.next in
-  if (Belt_Id.getEqInternal eq) cell.N.key key [@bs] then (
+  if (Belt_Id.getEqInternal eq) cell.N.key key [@u] then (
     prec.N.next <- cell_next;
     h.C.size <- h.C.size - 1)
   else
@@ -82,14 +82,14 @@ let remove h key =
   let eq = h.C.eq in
   let h_buckets = h.C.buckets in
   let i =
-    ((Belt_Id.getHashInternal h.C.hash) key [@bs]) land (A.length h_buckets - 1)
+    ((Belt_Id.getHashInternal h.C.hash) key [@u]) land (A.length h_buckets - 1)
   in
   let l = A.getUnsafe h_buckets i in
   match C.toOpt l with
   | None -> ()
   | Some cell -> (
       let next_cell = cell.N.next in
-      if (Belt_Id.getEqInternal eq) cell.N.key key [@bs] then (
+      if (Belt_Id.getEqInternal eq) cell.N.key key [@u] then (
         h.C.size <- h.C.size - 1;
         A.setUnsafe h_buckets i next_cell)
       else
@@ -98,7 +98,7 @@ let remove h key =
         | Some next_cell -> removeBucket ~eq h h_buckets i key cell next_cell)
 
 let rec addBucket h key cell ~eq =
-  if not ((Belt_Id.getEqInternal eq) cell.N.key key [@bs]) then
+  if not ((Belt_Id.getEqInternal eq) cell.N.key key [@u]) then
     let n = cell.N.next in
     match C.toOpt n with
     | None ->
@@ -109,7 +109,7 @@ let rec addBucket h key cell ~eq =
 let add0 h key ~hash ~eq =
   let h_buckets = h.C.buckets in
   let buckets_len = A.length h_buckets in
-  let i = ((Belt_Id.getHashInternal hash) key [@bs]) land (buckets_len - 1) in
+  let i = ((Belt_Id.getHashInternal hash) key [@u]) land (buckets_len - 1) in
   let l = A.getUnsafe h_buckets i in
   (match C.toOpt l with
   | None ->
@@ -121,7 +121,7 @@ let add0 h key ~hash ~eq =
 let add h key = add0 ~hash:h.C.hash ~eq:h.C.eq h key
 
 let rec memInBucket ~eq key cell =
-  ((Belt_Id.getEqInternal eq) cell.N.key key [@bs])
+  ((Belt_Id.getEqInternal eq) cell.N.key key [@u])
   ||
   match C.toOpt cell.N.next with
   | None -> false
@@ -130,7 +130,7 @@ let rec memInBucket ~eq key cell =
 let has h key =
   let eq, h_buckets = (h.C.eq, h.C.buckets) in
   let nid =
-    ((Belt_Id.getHashInternal h.C.hash) key [@bs]) land (A.length h_buckets - 1)
+    ((Belt_Id.getHashInternal h.C.hash) key [@u]) land (A.length h_buckets - 1)
   in
   let bucket = A.getUnsafe h_buckets nid in
   match C.toOpt bucket with
diff --git a/jscomp/others/belt_HashSet.mli b/jscomp/others/belt_HashSet.mli
index c043144ffc..68a8ef8dd9 100644
--- a/jscomp/others/belt_HashSet.mli
+++ b/jscomp/others/belt_HashSet.mli
@@ -33,14 +33,14 @@
       type t = int
       module I0 =
         (val Belt.Id.hashableU
-            ~hash:(fun[\@bs] (a : t)  -> a & 0xff_ff)
-            ~eq:(fun[\@bs] a b -> a = b)
+            ~hash:(fun[\@u] (a : t)  -> a & 0xff_ff)
+            ~eq:(fun[\@u] a b -> a = b)
         )
       let s0 = make ~id:(module I0) ~hintSize:40
       module I1 =
         (val Belt.Id.hashableU
-            ~hash:(fun[\@bs] (a : t)  -> a & 0xff)
-            ~eq:(fun[\@bs] a b -> a = b)
+            ~hash:(fun[\@u] (a : t)  -> a & 0xff)
+            ~eq:(fun[\@u] a b -> a = b)
         )
       let s1 = make ~id:(module I1) ~hintSize:40
     ]}
diff --git a/jscomp/others/node_process.ml b/jscomp/others/node_process.ml
index 6923455e9d..4ae9e654a9 100644
--- a/jscomp/others/node_process.ml
+++ b/jscomp/others/node_process.ml
@@ -41,7 +41,7 @@ external exit : int -> 'a = "exit" [@@mel.module "process"]
 external cwd : unit -> string = "cwd" [@@mel.module "process"]
 
 external uptime : t -> unit -> float = "uptime"
-  [@@mel.send]
+[@@mel.send]
 (** The process.uptime() method returns the number of seconds
    the current Node.js process has been running.) *)
 
@@ -52,4 +52,4 @@ external uptime : t -> unit -> float = "uptime"
 *)
 let putEnvVar key (var : string) = Js.Dict.set process##env key var
 
-let deleteEnvVar s = (Js.Dict.unsafeDeleteKey process##env s [@bs])
+let deleteEnvVar s = (Js.Dict.unsafeDeleteKey process##env s [@u])