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 ba9e0fd..6ddf194 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 (#50 by @kl0tl and @JordanMartinez)
 
 New features:
 
diff --git a/bower.json b/bower.json
index d96eae8..154ef73 100644
--- a/bower.json
+++ b/bower.json
@@ -16,14 +16,14 @@
     "package.json"
   ],
   "dependencies": {
-    "purescript-math": "^3.0.0",
-    "purescript-maybe": "^5.0.0",
-    "purescript-numbers": "^8.0.0",
-    "purescript-prelude": "^5.0.0"
+    "purescript-math": "master",
+    "purescript-maybe": "master",
+    "purescript-numbers": "master",
+    "purescript-prelude": "master"
   },
   "devDependencies": {
-    "purescript-assert": "^5.0.0",
-    "purescript-console": "^5.0.0",
-    "purescript-partial": "^3.0.0"
+    "purescript-assert": "master",
+    "purescript-console": "master",
+    "purescript-partial": "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/Int.js b/src/Data/Int.js
index 9900e5e..9829cce 100644
--- a/src/Data/Int.js
+++ b/src/Data/Int.js
@@ -1,6 +1,4 @@
-"use strict";
-
-exports.fromNumberImpl = function (just) {
+export const fromNumberImpl = function (just) {
   return function (nothing) {
     return function (n) {
       /* jshint bitwise: false */
@@ -9,11 +7,11 @@ exports.fromNumberImpl = function (just) {
   };
 };
 
-exports.toNumber = function (n) {
+export const toNumber = function (n) {
   return n;
 };
 
-exports.fromStringAsImpl = function (just) {
+export const fromStringAsImpl = function (just) {
   return function (nothing) {
     return function (radix) {
       var digits;
@@ -39,27 +37,27 @@ exports.fromStringAsImpl = function (just) {
   };
 };
 
-exports.toStringAs = function (radix) {
+export const toStringAs = function (radix) {
   return function (i) {
     return i.toString(radix);
   };
 };
 
 
-exports.quot = function (x) {
+export const quot = function (x) {
   return function (y) {
     /* jshint bitwise: false */
     return x / y | 0;
   };
 };
 
-exports.rem = function (x) {
+export const rem = function (x) {
   return function (y) {
     return x % y;
   };
 };
 
-exports.pow = function (x) {
+export const pow = function (x) {
   return function (y) {
     /* jshint bitwise: false */
     return Math.pow(x,y) | 0;
diff --git a/src/Data/Int/Bits.js b/src/Data/Int/Bits.js
index ed36ea4..49bbaff 100644
--- a/src/Data/Int/Bits.js
+++ b/src/Data/Int/Bits.js
@@ -1,50 +1,48 @@
-"use strict";
-
 // module Data.Int.Bits
 
-exports.and = function (n1) {
+export const and = function (n1) {
   return function (n2) {
     /* jshint bitwise: false */
     return n1 & n2;
   };
 };
 
-exports.or = function (n1) {
+export const or = function (n1) {
   return function (n2) {
     /* jshint bitwise: false */
     return n1 | n2;
   };
 };
 
-exports.xor = function (n1) {
+export const xor = function (n1) {
   return function (n2) {
     /* jshint bitwise: false */
     return n1 ^ n2;
   };
 };
 
-exports.shl = function (n1) {
+export const shl = function (n1) {
   return function (n2) {
     /* jshint bitwise: false */
     return n1 << n2;
   };
 };
 
-exports.shr = function (n1) {
+export const shr = function (n1) {
   return function (n2) {
     /* jshint bitwise: false */
     return n1 >> n2;
   };
 };
 
-exports.zshr = function (n1) {
+export const zshr = function (n1) {
   return function (n2) {
     /* jshint bitwise: false */
     return n1 >>> n2;
   };
 };
 
-exports.complement = function (n) {
+export const complement = function (n) {
   /* jshint bitwise: false */
   return ~n;
 };