diff --git a/CHANGES.md b/CHANGES.md
index 881f751..5ef2198 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -19,6 +19,8 @@
   ([#30](https://github.com/melange-community/melange-json/pull/30))
 - PPX: add support for `int64` in the runtime
   ([#33](https://github.com/melange-community/melange-json/pull/33))
+- PPX: remove `string_to_json` usage on js side
+  ([#35](https://github.com/melange-community/melange-json/pull/35))
 
 ## 1.3.0 (2024-08-28)
 
diff --git a/ppx/browser/ppx_deriving_json_js.ml b/ppx/browser/ppx_deriving_json_js.ml
index 3ebf157..5437daf 100644
--- a/ppx/browser/ppx_deriving_json_js.ml
+++ b/ppx/browser/ppx_deriving_json_js.ml
@@ -194,13 +194,13 @@ module To_json = struct
     | Vcs_record (n, r) ->
         let loc = n.loc in
         let n = Option.value ~default:n (vcs_attr_json_name r.rcd_ctx) in
-        let tag = [%expr string_to_json [%e estring ~loc:n.loc n.txt]] in
+        let tag = [%expr (Obj.magic [%e estring ~loc:n.loc n.txt]: Js.Json.t)] in
         let es = [ derive_of_record derive r es ] in
         as_json ~loc (pexp_array ~loc (tag :: es))
     | Vcs_tuple (n, t) ->
         let loc = n.loc in
         let n = Option.value ~default:n (vcs_attr_json_name t.tpl_ctx) in
-        let tag = [%expr string_to_json [%e estring ~loc:n.loc n.txt]] in
+        let tag = [%expr (Obj.magic [%e estring ~loc:n.loc n.txt]: Js.Json.t)] in
         let es = List.map2 t.tpl_types es ~f:derive in
         as_json ~loc (pexp_array ~loc (tag :: es))
 
diff --git a/ppx/test/ppx_deriving_json_js.t b/ppx/test/ppx_deriving_json_js.t
index d7eab10..3745e1c 100644
--- a/ppx/test/ppx_deriving_json_js.t
+++ b/ppx/test/ppx_deriving_json_js.t
@@ -406,14 +406,14 @@
     let rec sum_to_json =
       (fun x ->
          match x with
-         | A -> (Obj.magic [| string_to_json "A" |] : Js.Json.t)
+         | A -> (Obj.magic [| (Obj.magic "A" : Js.Json.t) |] : Js.Json.t)
          | B x_0 ->
-             (Obj.magic [| string_to_json "B"; int_to_json x_0 |]
+             (Obj.magic [| (Obj.magic "B" : Js.Json.t); int_to_json x_0 |]
                : Js.Json.t)
          | C { name = x_name } ->
              (Obj.magic
                 [|
-                  string_to_json "C";
+                  (Obj.magic "C" : Js.Json.t);
                   (Obj.magic [%mel.obj { name = string_to_json x_name }]
                     : Js.Json.t);
                 |]
@@ -472,7 +472,9 @@
          | S2 (x_0, x_1) ->
              (Obj.magic
                 [|
-                  string_to_json "S2"; int_to_json x_0; string_to_json x_1;
+                  (Obj.magic "S2" : Js.Json.t);
+                  int_to_json x_0;
+                  string_to_json x_1;
                 |]
                : Js.Json.t)
         : sum2 -> Js.Json.t)
@@ -532,7 +534,7 @@
     let rec other_to_json =
       (fun x ->
          match x with
-         | `C -> (Obj.magic [| string_to_json "C" |] : Js.Json.t)
+         | `C -> (Obj.magic [| (Obj.magic "C" : Js.Json.t) |] : Js.Json.t)
         : other -> Js.Json.t)
   
     let _ = other_to_json
@@ -595,9 +597,9 @@
     let rec poly_to_json =
       (fun x ->
          match x with
-         | `A -> (Obj.magic [| string_to_json "A" |] : Js.Json.t)
+         | `A -> (Obj.magic [| (Obj.magic "A" : Js.Json.t) |] : Js.Json.t)
          | `B x_0 ->
-             (Obj.magic [| string_to_json "B"; int_to_json x_0 |]
+             (Obj.magic [| (Obj.magic "B" : Js.Json.t); int_to_json x_0 |]
                : Js.Json.t)
          | #other as x -> other_to_json x
         : poly -> Js.Json.t)
@@ -663,7 +665,9 @@
          | `P2 (x_0, x_1) ->
              (Obj.magic
                 [|
-                  string_to_json "P2"; int_to_json x_0; string_to_json x_1;
+                  (Obj.magic "P2" : Js.Json.t);
+                  int_to_json x_0;
+                  string_to_json x_1;
                 |]
                : Js.Json.t)
         : poly2 -> Js.Json.t)
@@ -721,7 +725,8 @@
      fun x ->
       match x with
       | `C x_0 ->
-          (Obj.magic [| string_to_json "C"; a_to_json x_0 |] : Js.Json.t)
+          (Obj.magic [| (Obj.magic "C" : Js.Json.t); a_to_json x_0 |]
+            : Js.Json.t)
   
     let _ = c_to_json
   end [@@ocaml.doc "@inline"] [@@merlin.hide]
@@ -775,9 +780,10 @@
     let rec recur_to_json =
       (fun x ->
          match x with
-         | A -> (Obj.magic [| string_to_json "A" |] : Js.Json.t)
+         | A -> (Obj.magic [| (Obj.magic "A" : Js.Json.t) |] : Js.Json.t)
          | Fix x_0 ->
-             (Obj.magic [| string_to_json "Fix"; recur_to_json x_0 |]
+             (Obj.magic
+                [| (Obj.magic "Fix" : Js.Json.t); recur_to_json x_0 |]
                : Js.Json.t)
         : recur -> Js.Json.t)
   
@@ -842,9 +848,10 @@
     let rec polyrecur_to_json =
       (fun x ->
          match x with
-         | `A -> (Obj.magic [| string_to_json "A" |] : Js.Json.t)
+         | `A -> (Obj.magic [| (Obj.magic "A" : Js.Json.t) |] : Js.Json.t)
          | `Fix x_0 ->
-             (Obj.magic [| string_to_json "Fix"; polyrecur_to_json x_0 |]
+             (Obj.magic
+                [| (Obj.magic "Fix" : Js.Json.t); polyrecur_to_json x_0 |]
                : Js.Json.t)
         : polyrecur -> Js.Json.t)
   
@@ -900,8 +907,10 @@
     let rec evar_to_json =
       (fun x ->
          match x with
-         | A -> (Obj.magic [| string_to_json "A" |] : Js.Json.t)
-         | B -> (Obj.magic [| string_to_json "b_aliased" |] : Js.Json.t)
+         | A -> (Obj.magic [| (Obj.magic "A" : Js.Json.t) |] : Js.Json.t)
+         | B ->
+             (Obj.magic [| (Obj.magic "b_aliased" : Js.Json.t) |]
+               : Js.Json.t)
         : evar -> Js.Json.t)
   
     let _ = evar_to_json
@@ -964,8 +973,10 @@
     let rec epoly_to_json =
       (fun x ->
          match x with
-         | `a -> (Obj.magic [| string_to_json "A_aliased" |] : Js.Json.t)
-         | `b -> (Obj.magic [| string_to_json "b" |] : Js.Json.t)
+         | `a ->
+             (Obj.magic [| (Obj.magic "A_aliased" : Js.Json.t) |]
+               : Js.Json.t)
+         | `b -> (Obj.magic [| (Obj.magic "b" : Js.Json.t) |] : Js.Json.t)
         : epoly -> Js.Json.t)
   
     let _ = epoly_to_json
@@ -1019,9 +1030,11 @@
      fun x ->
       match x with
       | A x_0 ->
-          (Obj.magic [| string_to_json "A"; a_to_json x_0 |] : Js.Json.t)
+          (Obj.magic [| (Obj.magic "A" : Js.Json.t); a_to_json x_0 |]
+            : Js.Json.t)
       | B x_0 ->
-          (Obj.magic [| string_to_json "B"; b_to_json x_0 |] : Js.Json.t)
+          (Obj.magic [| (Obj.magic "B" : Js.Json.t); b_to_json x_0 |]
+            : Js.Json.t)
   
     let _ = p2_to_json
   end [@@ocaml.doc "@inline"] [@@merlin.hide]
@@ -1147,7 +1160,7 @@
          | A { a = x_a } ->
              (Obj.magic
                 [|
-                  string_to_json "A";
+                  (Obj.magic "A" : Js.Json.t);
                   (Obj.magic [%mel.obj { a = int_to_json x_a }] : Js.Json.t);
                 |]
                : Js.Json.t)
diff --git a/ppx/test/ppx_deriving_json_js_variants.e2e.t b/ppx/test/ppx_deriving_json_js_variants.e2e.t
new file mode 100644
index 0000000..27fa139
--- /dev/null
+++ b/ppx/test/ppx_deriving_json_js_variants.e2e.t
@@ -0,0 +1,26 @@
+
+  $ echo '(lang dune 3.11) 
+  > (using melange 0.1)' > dune-project
+
+  $ echo '
+  > (library
+  >  (name lib)
+  >  (modes melange)
+  >  (modules main)
+  >  (flags :standard -w -37-69)
+  >  (preprocess (pps melange.ppx melange-json.ppx)))
+  > (melange.emit
+  >  (alias js)
+  >  (target output)
+  >  (modules)
+  >  (libraries lib)
+  >  (module_systems commonjs))' > dune
+
+  $ echo '
+  > type sum = A [@@deriving json]
+  > let json = sum_to_json A
+  > ' >> main.ml
+
+Can build without having to open Ppx_deriving_json_runtime.Primitives
+
+  $ dune build @js