diff --git a/.eslintrc.json b/.eslintrc.json
index 17f167d..240b092 100644
--- a/.eslintrc.json
+++ b/.eslintrc.json
@@ -1,7 +1,7 @@
 {
-  "env": { "browser": true, "commonjs": true },
+  "env": { "browser": true },
   "extends": "eslint:recommended",
-  "parserOptions": { "ecmaVersion": 5 },
+  "parserOptions": { "ecmaVersion": 6, "sourceType": "module" },
   "rules": {
     "block-scoped-var": "error",
     "consistent-return": "error",
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 43f9f20..e16f413 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -16,6 +16,7 @@ jobs:
       - name: Set up PureScript toolchain
         uses: purescript-contrib/setup-purescript@main
         with:
+          purescript: "unstable"
           purs-tidy: "latest"
 
       - name: Cache PureScript dependencies
@@ -49,8 +50,17 @@ jobs:
       - name: Build the project
         run: npm run build
 
-      - name: Run tests
-        run: npm run test
+#      - name: Run tests
+#        run: npm run test
 
       - name: Check formatting
         run: purs-tidy check src test
+
+      - name: Verify Bower & Pulp
+        run: |
+          npm install bower pulp@16.0.0-0
+          npx bower install
+          npx pulp build -- --censor-lib --strict
+          if [ -d "test" ]; then
+            npx pulp test
+          fi
diff --git a/CHANGELOG.md b/CHANGELOG.md
index cbdb74d..a3aa617 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 (#27 by @JordanMartinez)
 
 New features:
 
diff --git a/bower.json b/bower.json
index 6881d61..d3262b4 100644
--- a/bower.json
+++ b/bower.json
@@ -17,11 +17,11 @@
     "package.json"
   ],
   "dependencies": {
-    "purescript-effect": "^3.0.0"
+    "purescript-effect": "master"
   },
   "devDependencies": {
-    "purescript-assert": "^5.0.0",
-    "purescript-console": "^5.0.0",
-    "purescript-refs": "^5.0.0"
+    "purescript-assert": "master",
+    "purescript-console": "master",
+    "purescript-refs": "master"
   }
 }
diff --git a/packages.dhall b/packages.dhall
index 7a6905b..582d6d3 100644
--- a/packages.dhall
+++ b/packages.dhall
@@ -1,4 +1,4 @@
 let upstream =
-      https://github.com/purescript/package-sets/releases/download/psc-0.14.3-20210722/packages.dhall sha256:1ceb43aa59436bf5601bac45f6f3781c4e1f0e4c2b8458105b018e5ed8c30f8c
+      https://raw.githubusercontent.com/purescript/package-sets/prepare-0.15/src/packages.dhall
 
 in  upstream
diff --git a/spago.dhall b/spago.dhall
index 59d1efd..419091e 100644
--- a/spago.dhall
+++ b/spago.dhall
@@ -1,6 +1,6 @@
 { name = "js-timers"
 , dependencies =
-  [ "assert", "console", "effect", "prelude", "psci-support", "refs" ]
+  [ "assert", "console", "effect", "prelude", "refs" ]
 , packages = ./packages.dhall
 , sources = [ "src/**/*.purs", "test/**/*.purs" ]
 }
diff --git a/src/Effect/Timer.js b/src/Effect/Timer.js
index 50ce0de..b535175 100644
--- a/src/Effect/Timer.js
+++ b/src/Effect/Timer.js
@@ -1,30 +1,28 @@
 /* no-redeclare global exports */
-"use strict";
-
-exports.setTimeout = function (ms) {
+export function setTimeout(ms) {
   return function (fn) {
     return function () {
       return setTimeout(fn, ms);
     };
   };
-};
+}
 
-exports.clearTimeout = function (id) {
+export function clearTimeout(id) {
   return function () {
     clearTimeout(id);
   };
-};
+}
 
-exports.setInterval = function (ms) {
+export function setInterval(ms) {
   return function (fn) {
     return function () {
       return setInterval(fn, ms);
     };
   };
-};
+}
 
-exports.clearInterval = function (id) {
+export function clearInterval(id) {
   return function () {
     clearInterval(id);
   };
-};
+}