diff --git a/bisect_ppx.opam b/bisect_ppx.opam
index 77a20062..d68c7372 100644
--- a/bisect_ppx.opam
+++ b/bisect_ppx.opam
@@ -23,6 +23,7 @@ depends: [
   "dune" {>= "2.7.0"}
   "ocaml" {>= "4.03.0"}
   "ppxlib" {>= "0.28.0"}
+  "melange"
 
   "dune" {with-test & >= "3.0.0"}
   "ocamlformat" {with-test & = "0.16.0"}
diff --git a/dune-project b/dune-project
index e1e4354c..67e6bdf3 100644
--- a/dune-project
+++ b/dune-project
@@ -1,2 +1,5 @@
-(lang dune 2.7)
+(lang dune 3.8)
+
+(using melange 0.1)
+
 (cram enable)
diff --git a/src/common/dune b/src/common/dune
index 385c41a0..721333fe 100644
--- a/src/common/dune
+++ b/src/common/dune
@@ -1,4 +1,5 @@
 (library
  (name bisect_common)
+ (modes :standard melange)
  (public_name bisect_ppx.common)
  (synopsis "Bisect_ppx internal functions (internal)"))
diff --git a/src/ppx/dune b/src/ppx/dune
index fa344af7..68415483 100644
--- a/src/ppx/dune
+++ b/src/ppx/dune
@@ -7,7 +7,7 @@
  (kind ppx_rewriter)
  (instrumentation.backend (ppx bisect_ppx))
  (synopsis "Code coverage for OCaml")
- (ppx_runtime_libraries bisect_ppx.runtime)
+ (ppx_runtime_libraries bisect_ppx.runtime_melange)
  (preprocess (pps ppxlib.metaquot))
  (flags (:standard -open Ocaml_shadow))
  (libraries bisect_ppx.common ppxlib str))
diff --git a/src/runtime/js/dune b/src/runtime/js/dune
new file mode 100644
index 00000000..e3d9efc1
--- /dev/null
+++ b/src/runtime/js/dune
@@ -0,0 +1,7 @@
+(library
+ (name bisect)
+ (modes melange)
+ (public_name bisect_ppx.runtime_melange)
+ (synopsis "Bisect_ppx runtime library for Melange")
+ (libraries bisect_common melange)
+ (preprocess (pps melange.ppx)))
diff --git a/src/runtime/js/jest.ml b/src/runtime/js/jest.ml
index e986f8e7..d4ec2c70 100644
--- a/src/runtime/js/jest.ml
+++ b/src/runtime/js/jest.ml
@@ -7,12 +7,11 @@
 
    this will cause timeout in Jest because Jest will wait until you manually
    invoke param.done() within afterAll. *)
-external afterAll : ((unit -> unit) [@bs]) -> unit = "afterAll"
-  [@@bs.val]
+external afterAll : ((unit -> unit) [@u]) -> unit = "afterAll"
 
 let () =
   afterAll
     ((fun ()  ->
       Runtime.write_coverage_data ();
       Runtime.reset_coverage_data ())
-    [@bs])
+    [@u])
diff --git a/src/runtime/js/runtime.ml b/src/runtime/js/runtime.ml
index 7078db6c..1e51a5dc 100644
--- a/src/runtime/js/runtime.ml
+++ b/src/runtime/js/runtime.ml
@@ -13,20 +13,20 @@ struct
   struct
     external openSync :
       string ->
-      ([ `Read [@as "r"]
-      | `Read_write [@as "r+"]
-      | `Read_write_sync [@as "rs+"]
-      | `Write [@as "w"]
-      | `Write_fail_if_exists [@as "wx"]
-      | `Write_read [@as "w+"]
-      | `Write_read_fail_if_exists [@as "wx+"]
-      | `Append [@as "a"]
-      | `Append_fail_if_exists [@as "ax"]
-      | `Append_read [@as "a+"]
-      | `Append_read_fail_if_exists [@as "ax+"] ]
-      [@string]) ->
+      ([ `Read [@mel.as "r"]
+      | `Read_write [@mel.as "r+"]
+      | `Read_write_sync [@mel.as "rs+"]
+      | `Write [@mel.as "w"]
+      | `Write_fail_if_exists [@mel.as "wx"]
+      | `Write_read [@mel.as "w+"]
+      | `Write_read_fail_if_exists [@mel.as "wx+"]
+      | `Append [@mel.as "a"]
+      | `Append_fail_if_exists [@mel.as "ax"]
+      | `Append_read [@mel.as "a+"]
+      | `Append_read_fail_if_exists [@mel.as "ax+"] ]
+      [@mel.string]) ->
       unit = "openSync"
-      [@@module "fs"]
+      [@@mel.module "fs"]
 
     type encoding = [
       | `hex
@@ -42,7 +42,7 @@ struct
 
     external writeFileSync : string -> string -> encoding -> unit =
       "writeFileSync"
-      [@@val] [@@module "fs"]
+      [@@mel.module "fs"]
   end
 end
 
@@ -70,7 +70,7 @@ let write_coverage_data () =
 let reset_coverage_data =
   Bisect_common.reset_counters
 
-let node_at_exit = [%bs.raw {|
+let node_at_exit: (unit -> unit) -> unit = [%mel.raw {|
   function (callback) {
     if (typeof process !== 'undefined' && typeof process.on !== 'undefined')
       process.on("exit", callback);
diff --git a/src/runtime/native/dune b/src/runtime/native/dune
index 76ae2c33..6dc4f703 100644
--- a/src/runtime/native/dune
+++ b/src/runtime/native/dune
@@ -1,5 +1,5 @@
 (library
- (name bisect)
+ (name bisect_native)
  (public_name bisect_ppx.runtime)
  (synopsis "Bisect_ppx runtime library (internal)")
  (libraries bisect_ppx.common unix))