diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
new file mode 100644
index 0000000..648c95b
--- /dev/null
+++ b/.github/workflows/main.yml
@@ -0,0 +1,32 @@
+name: build
+on: [push, pull_request]
+jobs:
+  run:
+    name: Build
+    strategy:
+      matrix:
+        os: [macos-latest, ubuntu-latest, windows-latest]
+        ocaml: [ '4.08.0', '4.03.0', '4.11.0' ]
+    runs-on: ${{ matrix.os }}
+    steps:
+    - uses: actions/checkout@main
+    - uses: avsm/setup-ocaml@v1
+      with:
+        ocaml-version: ${{ matrix.ocaml }}
+    - name: cache opam
+      id: cache-opam
+      uses: actions/cache@v2
+      with:
+        path: _opam
+        key: opam-${{matrix.operating-system}}-${{matrix.ocaml-version}}
+    - run: opam pin -n .
+      if: steps.cache-opam.outputs.cache-hit != 'true'
+    - run: opam depext -yt iter
+      if: steps.cache-opam.outputs.cache-hit != 'true'
+    - run: opam install -t . --deps-only
+      if: ${{ matrix.os != 'windows-latest' }} and ${{ steps.cache-opam.outputs.cache-hit != 'true' }}
+    - run: opam install . --deps-only  # no test deps
+      if: ${{ matrix.os == 'windows-latest' }} and ${{ steps.cache-opam.outputs.cache-hit != 'true' }}
+    - run: opam exec -- dune build
+    - run: opam exec -- dune runtest
+      if: ${{ matrix.os != 'windows-latest' }}
diff --git a/.travis.yml b/.travis.yml
deleted file mode 100644
index 740eda7..0000000
--- a/.travis.yml
+++ /dev/null
@@ -1,16 +0,0 @@
-language: c
-install: wget https://raw.githubusercontent.com/ocaml/ocaml-ci-scripts/master/.travis-docker.sh
-script: bash -ex .travis-docker.sh
-services:
-- docker
-env:
-  global:
-  - PINS="iter:."
-  - DISTRO="ubuntu-16.04"
-  matrix:
-  - PACKAGE="iter" OCAML_VERSION="4.02.3" EXTRA_DEPS="base-bigarray" TESTS=false
-  - PACKAGE="iter" OCAML_VERSION="4.03" EXTRA_DEPS="base-bigarray"
-  - PACKAGE="iter" OCAML_VERSION="4.04" EXTRA_DEPS="base-bigarray"
-    #- PACKAGE="iter" OCAML_VERSION="4.05" EXTRA_DEPS="base-bigarray"
-  - PACKAGE="iter" OCAML_VERSION="4.06" EXTRA_DEPS="base-bigarray"
-  - PACKAGE="iter" OCAML_VERSION="4.07" EXTRA_DEPS="base-bigarray"
diff --git a/README.md b/README.md
index 95a9340..4c8f158 100644
--- a/README.md
+++ b/README.md
@@ -1,4 +1,4 @@
-# Iter [![build status](https://travis-ci.org/c-cube/iter.svg?branch=master)](https://travis-ci.org/c-cube/iter) [![docs](https://img.shields.io/badge/doc-online-blue.svg)][doc]
+# Iter  ![build](https://github.com/c-cube/iter/workflows/build/badge.svg)
 
 Clean and efficient loop fusion for all your iterating needs!
 
diff --git a/iter.opam b/iter.opam
index a833324..06307c6 100644
--- a/iter.opam
+++ b/iter.opam
@@ -13,6 +13,7 @@ build: [
 depends: [
   "base-bytes"
   "result"
+  "ocaml" { >= "4.03.0" }
   "dune" { >= "1.1" }
   "dune-configurator"
   "qcheck" {with-test}
diff --git a/sequence.opam b/sequence.opam
deleted file mode 100644
index 89a8ff9..0000000
--- a/sequence.opam
+++ /dev/null
@@ -1,21 +0,0 @@
-opam-version: "2.0"
-name: "sequence"
-version: "1.1"
-author: "Simon Cruanes"
-maintainer: "simon.cruanes.2007@m4x.org"
-license: "BSD-2-clauses"
-synopsis: "Compatibility package for `iter`"
-build: [
-  ["dune" "build" "@install" "-p" name "-j" jobs]
-]
-depends: [
-  "iter"
-]
-tags: [ "sequence" "iterator" "iter" "fold" ]
-homepage: "https://github.com/c-cube/iter/"
-depopts: [
-  "base-bigarray"
-]
-doc: "https://c-cube.github.io/iter/"
-bug-reports: "https://github.com/c-cube/iter/issues"
-dev-repo: "git+https://github.com/c-cube/iter.git"