diff --git a/.eslintrc.json b/.eslintrc.json
index 84cef4f..1c6afb9 100644
--- a/.eslintrc.json
+++ b/.eslintrc.json
@@ -1,11 +1,9 @@
 {
   "parserOptions": {
-    "ecmaVersion": 5
+    "ecmaVersion": 6,
+    "sourceType": "module"
   },
   "extends": "eslint:recommended",
-  "env": {
-    "commonjs": true
-  },
   "rules": {
     "strict": [2, "global"],
     "block-scoped-var": 2,
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 43d2897..b6ebf3a 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -13,6 +13,8 @@ jobs:
       - uses: actions/checkout@v2
 
       - uses: purescript-contrib/setup-purescript@main
+        with:
+          purescript: "unstable"
 
       - uses: actions/setup-node@v1
         with:
diff --git a/CHANGELOG.md b/CHANGELOG.md
index e6e1e9c..2024a7c 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -5,6 +5,7 @@ Notable changes to this project are documented in this file. The format is based
 ## [Unreleased]
 
 Breaking changes:
+- Migrate FFI to ES modules (#146 by @kl0tl and @JordanMartinez)
 
 New features:
 
diff --git a/bower.json b/bower.json
index 01ba9de..f90a2ff 100644
--- a/bower.json
+++ b/bower.json
@@ -17,23 +17,23 @@
     "package.json"
   ],
   "dependencies": {
-    "purescript-bifunctors": "^5.0.0",
-    "purescript-const": "^5.0.0",
-    "purescript-control": "^5.0.0",
-    "purescript-either": "^5.0.0",
-    "purescript-functors": "^4.0.0",
-    "purescript-identity": "^5.0.0",
-    "purescript-maybe": "^5.0.0",
-    "purescript-newtype": "^4.0.0",
-    "purescript-orders": "^5.0.0",
-    "purescript-prelude": "^5.0.0",
-    "purescript-tuples": "^6.0.0"
+    "purescript-bifunctors": "master",
+    "purescript-const": "master",
+    "purescript-control": "master",
+    "purescript-either": "master",
+    "purescript-functors": "master",
+    "purescript-identity": "master",
+    "purescript-maybe": "master",
+    "purescript-newtype": "master",
+    "purescript-orders": "master",
+    "purescript-prelude": "master",
+    "purescript-tuples": "master"
   },
   "devDependencies": {
-    "purescript-assert": "^5.0.0",
-    "purescript-console": "^5.0.0",
-    "purescript-integers": "^5.0.0",
-    "purescript-math": "^3.0.0",
-    "purescript-unsafe-coerce": "^5.0.0"
+    "purescript-assert": "master",
+    "purescript-console": "master",
+    "purescript-integers": "master",
+    "purescript-math": "master",
+    "purescript-unsafe-coerce": "master"
   }
 }
diff --git a/package.json b/package.json
index fd4391e..a1d6811 100644
--- a/package.json
+++ b/package.json
@@ -7,8 +7,8 @@
   },
   "devDependencies": {
     "eslint": "^7.15.0",
-    "pulp": "^15.0.0",
-    "purescript-psa": "^0.8.0",
+    "pulp": "16.0.0-0",
+    "purescript-psa": "^0.8.2",
     "rimraf": "^3.0.2"
   }
 }
diff --git a/src/Data/Foldable.js b/src/Data/Foldable.js
index bbdf340..8c5cbe4 100644
--- a/src/Data/Foldable.js
+++ b/src/Data/Foldable.js
@@ -1,6 +1,4 @@
-"use strict";
-
-exports.foldrArray = function (f) {
+export const foldrArray = function (f) {
   return function (init) {
     return function (xs) {
       var acc = init;
@@ -13,7 +11,7 @@ exports.foldrArray = function (f) {
   };
 };
 
-exports.foldlArray = function (f) {
+export const foldlArray = function (f) {
   return function (init) {
     return function (xs) {
       var acc = init;
diff --git a/src/Data/FunctorWithIndex.js b/src/Data/FunctorWithIndex.js
index 65b2816..884e842 100644
--- a/src/Data/FunctorWithIndex.js
+++ b/src/Data/FunctorWithIndex.js
@@ -1,6 +1,4 @@
-"use strict";
-
-exports.mapWithIndexArray = function (f) {
+export const mapWithIndexArray = function (f) {
   return function (xs) {
     var l = xs.length;
     var result = Array(l);
diff --git a/src/Data/Traversable.js b/src/Data/Traversable.js
index 269ebe1..9f4248c 100644
--- a/src/Data/Traversable.js
+++ b/src/Data/Traversable.js
@@ -1,8 +1,6 @@
-"use strict";
-
 // jshint maxparams: 3
 
-exports.traverseArrayImpl = (function () {
+export const traverseArrayImpl = (function () {
   function array1(a) {
     return [a];
   }
diff --git a/test/Main.js b/test/Main.js
index f7661fb..fc3b2ff 100644
--- a/test/Main.js
+++ b/test/Main.js
@@ -1,14 +1,12 @@
-"use strict";
-
-exports.arrayFrom1UpTo = function (n) {
+export function arrayFrom1UpTo(n) {
   var result = [];
   for (var i = 1; i <= n; i++) {
     result.push(i);
   }
   return result;
-};
+}
 
-exports.arrayReplicate = function (n) {
+export function arrayReplicate(n) {
   return function (x) {
     var result = [];
     for (var i = 1; i <= n; i++) {
@@ -16,17 +14,17 @@ exports.arrayReplicate = function (n) {
     }
     return result;
   };
-};
+}
 
-exports.mkNEArray = function (nothing) {
+export function mkNEArray(nothing) {
   return function (just) {
     return function (arr) {
       return arr.length > 0 ? just(arr) : nothing;
     };
   };
-};
+}
 
-exports.foldMap1NEArray = function (append) {
+export function foldMap1NEArray(append) {
   return function (f) {
     return function (arr) {
       var acc = f(arr[0]);
@@ -37,4 +35,4 @@ exports.foldMap1NEArray = function (append) {
       return acc;
     };
   };
-};
+}