diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 266172a..13a43ca 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -9,56 +9,29 @@ on:
 jobs:
   build:
     runs-on: ubuntu-latest
-
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v4
 
-      - name: Set up PureScript toolchain
+      - name: Set up a PureScript toolchain
         uses: purescript-contrib/setup-purescript@main
         with:
-          purescript: "unstable"
+          purescript: "latest"
           purs-tidy: "latest"
+          spago: "unstable"
 
       - name: Cache PureScript dependencies
-        uses: actions/cache@v2
+        uses: actions/cache@v4
         with:
-          key: ${{ runner.os }}-spago-${{ hashFiles('**/*.dhall') }}
+          key: ${{ runner.os }}-spago-${{ hashFiles('**/spago.lock') }}
           path: |
             .spago
             output
 
-      - name: Set up Node toolchain
-        uses: actions/setup-node@v2
-        with:
-          node-version: "14.x"
-
-      - name: Cache NPM dependencies
-        uses: actions/cache@v2
-        env:
-          cache-name: cache-node-modules
-        with:
-          path: ~/.npm
-          key: ${{ runner.os }}-build-${{ env.cache-name }}-${{ hashFiles('**/package.json') }}
-          restore-keys: |
-            ${{ runner.os }}-build-${{ env.cache-name }}-
-            ${{ runner.os }}-build-
-            ${{ runner.os }}-
-
-      - name: Install NPM dependencies
-        run: npm install
-
-      - name: Build the project
-        run: npm run build
+      - name: Build source
+        run: spago build --censor-stats --strict --ensure-ranges --pedantic-packages
 
       - name: Run tests
-        run: npm run test
+        run: spago test --offline --censor-stats --strict --pedantic-packages
 
-      - name: Check formatting
+      - name: Verify 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
-          npx pulp test
diff --git a/bower.json b/bower.json
deleted file mode 100644
index bbf1da8..0000000
--- a/bower.json
+++ /dev/null
@@ -1,42 +0,0 @@
-{
-  "name": "purescript-aff",
-  "homepage": "https://github.com/slamdata/purescript-aff",
-  "description": "Asynchronous effect monad",
-  "repository": {
-    "type": "git",
-    "url": "https://github.com/purescript-contrib/purescript-aff.git"
-  },
-  "license": "Apache-2.0",
-  "ignore": [
-    "**/.*",
-    "bower_components",
-    "node_modules",
-    "output",
-    "test",
-    "bower.json",
-    "package.json"
-  ],
-  "dependencies": {
-    "purescript-arrays": "^7.0.0",
-    "purescript-bifunctors": "^6.0.0",
-    "purescript-control": "^6.0.0",
-    "purescript-datetime": "^6.0.0",
-    "purescript-effect": "^4.0.0",
-    "purescript-either": "^6.0.0",
-    "purescript-exceptions": "^6.0.0",
-    "purescript-foldable-traversable": "^6.0.0",
-    "purescript-functions": "^6.0.0",
-    "purescript-maybe": "^6.0.0",
-    "purescript-newtype": "^5.0.0",
-    "purescript-parallel": "^7.0.0",
-    "purescript-prelude": "^6.0.0",
-    "purescript-refs": "^6.0.0",
-    "purescript-tailrec": "^6.0.0",
-    "purescript-transformers": "^6.0.0",
-    "purescript-unsafe-coerce": "^6.0.0"
-  },
-  "devDependencies": {
-    "purescript-minibench": "^4.0.0",
-    "purescript-assert": "^6.0.0"
-  }
-}
diff --git a/package.json b/package.json
index 1079001..8867c04 100644
--- a/package.json
+++ b/package.json
@@ -1,11 +1,19 @@
 {
   "private": true,
+  "name": "purescript-aff",
+  "homepage": "https://github.com/slamdata/purescript-aff",
+  "description": "Asynchronous effect monad",
+  "repository": {
+    "type": "git",
+    "url": "https://github.com/purescript-contrib/purescript-aff.git"
+  },
+  "license": "Apache-2.0",
   "scripts": {
-    "build": "eslint src && spago build --purs-args '--censor-lib --strict'",
-    "test": "spago test --no-install"
+    "build": "eslint src && spago build --censor-stats --strict --ensure-ranges --pedantic-packages",
+    "test": "spago test --offline"
   },
   "devDependencies": {
-    "eslint": "^7.10.0",
-    "purescript-psa": "^0.8.2"
+    "eslint": "^9.12.0",
+    "purescript-psa": "^0.9.0"
   }
 }
diff --git a/packages.dhall b/packages.dhall
deleted file mode 100644
index e2fa4cb..0000000
--- a/packages.dhall
+++ /dev/null
@@ -1,5 +0,0 @@
-let upstream =
-      https://github.com/purescript/package-sets/releases/download/psc-0.15.4-20220725/packages.dhall
-        sha256:e56fbdf33a5afd2a610c81f8b940b413a638931edb41532164e641bb2a9ec29c
-
-in  upstream
diff --git a/spago.dhall b/spago.dhall
deleted file mode 100644
index 4070681..0000000
--- a/spago.dhall
+++ /dev/null
@@ -1,28 +0,0 @@
-{ name = "aff"
-, dependencies =
-  [ "arrays"
-  , "assert"
-  , "bifunctors"
-  , "console"
-  , "control"
-  , "datetime"
-  , "effect"
-  , "either"
-  , "exceptions"
-  , "foldable-traversable"
-  , "functions"
-  , "maybe"
-  , "minibench"
-  , "newtype"
-  , "parallel"
-  , "partial"
-  , "prelude"
-  , "refs"
-  , "st"
-  , "tailrec"
-  , "transformers"
-  , "unsafe-coerce"
-  ]
-, packages = ./packages.dhall
-, sources = [ "src/**/*.purs", "test/**/*.purs" ]
-}
diff --git a/spago.yaml b/spago.yaml
new file mode 100644
index 0000000..33ab148
--- /dev/null
+++ b/spago.yaml
@@ -0,0 +1,35 @@
+package:
+  name: aff
+  publish:
+    license: MIT
+    version: 9.0.0
+    location:
+      githubOwner: purescript-contrib
+      githubRepo: purescript-aff
+  dependencies:
+    - control: ">=6.0.0 <7.0.0"
+    - datetime: ">=6.1.0 <7.0.0"
+    - effect: ">=4.0.0 <5.0.0"
+    - either: ">=6.1.0 <7.0.0"
+    - exceptions: ">=6.1.0 <7.0.0"
+    - functions: ">=6.0.0 <7.0.0"
+    - newtype: ">=5.0.0 <6.0.0"
+    - parallel: ">=7.0.0 <8.0.0"
+    - partial: ">=4.0.0 <5.0.0"
+    - prelude: ">=6.0.1 <7.0.0"
+    - st: ">=6.2.0 <7.0.0"
+    - tailrec: ">=6.1.0 <7.0.0"
+    - transformers: ">=6.1.0 <7.0.0"
+    - unsafe-coerce: ">=6.0.0 <7.0.0"
+  test:
+    main: Test.Main
+    dependencies:
+      - arrays
+      - assert
+      - bifunctors
+      - console
+      - foldable-traversable
+      - maybe
+      - minibench
+      - refs
+workspace: {}