diff --git a/dune b/dune
index 2fb1b0e..2aac24f 100644
--- a/dune
+++ b/dune
@@ -1 +1 @@
-(ignored_subdirs (doc esy.lock lib node_modules))
+(dirs src test)
diff --git a/dune-project b/dune-project
index de4fc20..8a175b0 100644
--- a/dune-project
+++ b/dune-project
@@ -1 +1,2 @@
-(lang dune 1.0)
+(lang dune 3.8)
+(using melange 0.1)
diff --git a/promise.opam b/promise.opam
index 195cd4c..945d9e9 100644
--- a/promise.opam
+++ b/promise.opam
@@ -17,6 +17,7 @@ depends: [
   "ocaml"
   "reason" {build & >= "3.3.2"}
   "result"
+  "melange"
 ]
 
 build: [
diff --git a/src/js/dune b/src/js/dune
new file mode 100644
index 0000000..731b074
--- /dev/null
+++ b/src/js/dune
@@ -0,0 +1,10 @@
+(library
+ (name promise_js)
+ (public_name promise.melange)
+ (modes melange)
+ (wrapped false)
+ (libraries melange.belt)
+ (preprocess
+  (pps melange.ppx))
+ (flags
+  (:standard -w +A-102-20)))
diff --git a/src/js/promise.re b/src/js/promise.re
index a63de20..31bc4ef 100644
--- a/src/js/promise.re
+++ b/src/js/promise.re
@@ -19,7 +19,7 @@ let onUnhandledException = ref(exn => {
 
 
 
-[%%bs.raw {|
+[%%mel.raw {|
 function PromiseBox(p) {
     this.nested = p;
 };
@@ -90,7 +90,6 @@ module Js_ = {
 
   external relax: promise('a) => rejectable('a, _) = "%identity";
 
-  [@bs.val]
   external jsNew:
     (('a => unit) => ('e => unit) => unit) => rejectable('a, 'e) = "make";
 
@@ -105,10 +104,8 @@ module Js_ = {
     (p, resolve^, reject^);
   };
 
-  [@bs.val]
   external resolved: 'a => rejectable('a, _) = "resolved";
 
-  [@bs.val]
   external flatMap:
     (rejectable('a, 'e), 'a => rejectable('b, 'e)) => rejectable('b, 'e) =
       "then";
@@ -125,20 +122,16 @@ module Js_ = {
       v
     });
 
-  [@bs.scope "Promise"]
-  [@bs.val]
+  [@mel.scope "Promise"]
   external rejected: 'e => rejectable(_, 'e) = "reject";
 
-  [@bs.val]
   external catch:
     (rejectable('a, 'e), 'e => rejectable('a, 'e2)) => rejectable('a, 'e2) =
       "catch_";
 
-  [@bs.val]
   external unbox: 'a => 'a = "unbox";
 
-  [@bs.scope "Promise"]
-  [@bs.val]
+  [@mel.scope "Promise"]
   external jsAll: 'a => 'b = "all";
 
   let allArray = promises =>
@@ -162,8 +155,7 @@ module Js_ = {
   let all6 = (p1, p2, p3, p4, p5, p6) =>
     jsAll((p1, p2, p3, p4, p5, p6));
 
-  [@bs.scope "Promise"]
-  [@bs.val]
+  [@mel.scope "Promise"]
   external jsRace: array(rejectable('a, 'e)) => rejectable('a, 'e) = "race";
 
   let race = promises =>
diff --git a/test/bundle/dune b/test/bundle/dune
new file mode 100644
index 0000000..b6379f1
--- /dev/null
+++ b/test/bundle/dune
@@ -0,0 +1,4 @@
+(library
+ (name bundle)
+ (modes melange)
+ (libraries melange.belt promise.melange))
diff --git a/test/dune b/test/dune
deleted file mode 100644
index 79c4217..0000000
--- a/test/dune
+++ /dev/null
@@ -1,3 +0,0 @@
-(executable
- (name test_main)
- (libraries isoresult promise test_ffi))
diff --git a/test/ffi/js/dune b/test/ffi/js/dune
new file mode 100644
index 0000000..63d61b5
--- /dev/null
+++ b/test/ffi/js/dune
@@ -0,0 +1,11 @@
+(library
+ (name test_ffi_js)
+ (modes melange)
+ (libraries framework_js)
+ (wrapped false)
+ (preprocess
+  (pps melange.ppx)))
+
+(copy_files
+ (mode fallback)
+ (files ../native/*.re))
diff --git a/test/js/test_ffi.re b/test/ffi/js/test_ffi.re
similarity index 98%
rename from test/js/test_ffi.re
rename to test/ffi/js/test_ffi.re
index 18346c0..5035fb0 100644
--- a/test/js/test_ffi.re
+++ b/test/ffi/js/test_ffi.re
@@ -4,7 +4,7 @@
 
 
 
-[%%bs.raw {|
+[%%mel.raw {|
 function isPromise (p) {
     return (p instanceof Promise);
 }
@@ -14,13 +14,8 @@ function isPromiseLike(v) {
 };
 |}];
 
-[@bs.val]
 external isPromise: Promise.Js.t(_, _) => bool = "isPromise";
-
-[@bs.val]
 external jsPromiseIsPromise: Js.Promise.t(_) => bool = "isPromise";
-
-[@bs.val]
 external jsPromiseIsPromiseLike: Js.Promise.t(_) => bool = "isPromiseLike";
 
 
@@ -70,7 +65,7 @@ let interopTests = Framework.suite("interop", [
   }),
 
   test("js promise is reason-promise", () => {
-    let js_promise: Promise.t(int) = [%bs.raw {|Promise.resolve(1)|}];
+    let js_promise: Promise.t(int) = [%mel.raw {|Promise.resolve(1)|}];
     js_promise
     ->Promise.flatMap(n => Promise.resolved(n + 1))
     ->Promise.flatMap(n => Promise.resolved(n == 2));
@@ -78,7 +73,7 @@ let interopTests = Framework.suite("interop", [
 
   test("reason-promise as js argument", () => {
     module Then = {
-      [@bs.send.pipe: Promise.t('a)]
+      [@mel.send.pipe: Promise.t('a)]
       external js_then: ('a => Promise.t('b)) => Promise.t('b) =
         "then";
     };
@@ -243,7 +238,7 @@ let soundnessTests = Framework.suite("soundness", [
 
   [@ocaml.warning "-33"]
   test("resolved: Almost-Promise-like", () => {
-    let open Js_OO;
+    /* let open Js_OO; */
     Promise.resolved(makeAlmostPromiseLike(42))
     ->Promise.flatMap(x => Promise.resolved(x##_then == 42));
   }),
diff --git a/test/ffi/native/dune b/test/ffi/native/dune
new file mode 100644
index 0000000..04c668e
--- /dev/null
+++ b/test/ffi/native/dune
@@ -0,0 +1,3 @@
+(library
+ (name test_ffi)
+ (libraries framework))
diff --git a/test/native/test_ffi.re b/test/ffi/native/test_ffi.re
similarity index 100%
rename from test/native/test_ffi.re
rename to test/ffi/native/test_ffi.re
diff --git a/test/framework/dune b/test/framework/dune
deleted file mode 100644
index 5149281..0000000
--- a/test/framework/dune
+++ /dev/null
@@ -1,3 +0,0 @@
-(library
- (name framework)
- (libraries promise run))
diff --git a/test/framework/js/dune b/test/framework/js/dune
new file mode 100644
index 0000000..5af6c4e
--- /dev/null
+++ b/test/framework/js/dune
@@ -0,0 +1,9 @@
+(library
+ (name framework_js)
+ (modes melange)
+ (wrapped false)
+ (libraries promise_js))
+
+(copy_files
+ (mode fallback)
+ (files ../native/*.re))
diff --git a/test/framework/native/dune b/test/framework/native/dune
index 0b65a56..1ffa308 100644
--- a/test/framework/native/dune
+++ b/test/framework/native/dune
@@ -1,3 +1,3 @@
 (library
- (name run)
+ (name framework)
  (libraries promise))
diff --git a/test/framework/framework.re b/test/framework/native/framework.re
similarity index 100%
rename from test/framework/framework.re
rename to test/framework/native/framework.re
diff --git a/test/framework/framework.rei b/test/framework/native/framework.rei
similarity index 100%
rename from test/framework/framework.rei
rename to test/framework/native/framework.rei
diff --git a/test/isoresult/js/dune b/test/isoresult/js/dune
new file mode 100644
index 0000000..9c1feec
--- /dev/null
+++ b/test/isoresult/js/dune
@@ -0,0 +1,5 @@
+(library
+ (name isoresult_js)
+ (modes melange)
+ (wrapped false)
+ (libraries melange.belt))
diff --git a/test/js/benchmark.re b/test/js/benchmark.re
index bfcfd86..c3022c7 100644
--- a/test/js/benchmark.re
+++ b/test/js/benchmark.re
@@ -8,7 +8,6 @@ let test = Framework.test;
 
 
 
-[@bs.val]
 external hrtime: unit => (int, int) = "process.hrtime";
 
 let hrtime = () => {
diff --git a/test/js/dune b/test/js/dune
new file mode 100644
index 0000000..f89a822
--- /dev/null
+++ b/test/js/dune
@@ -0,0 +1,9 @@
+(copy_files
+ (mode fallback)
+ (files ../native/*.re))
+
+(melange.emit
+ (target test)
+ (libraries framework_js promise_js isoresult_js test_ffi_js)
+ (preprocess
+  (pps melange.ppx)))
diff --git a/test/native/dune b/test/native/dune
index 04c668e..79c4217 100644
--- a/test/native/dune
+++ b/test/native/dune
@@ -1,3 +1,3 @@
-(library
- (name test_ffi)
- (libraries framework))
+(executable
+ (name test_main)
+ (libraries isoresult promise test_ffi))
diff --git a/test/test_main.re b/test/native/test_main.re
similarity index 100%
rename from test/test_main.re
rename to test/native/test_main.re
diff --git a/test/test_promise.re b/test/native/test_promise.re
similarity index 100%
rename from test/test_promise.re
rename to test/native/test_promise.re