diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
new file mode 100644
index 00000000..637969a3
--- /dev/null
+++ b/.github/workflows/ci.yml
@@ -0,0 +1,55 @@
+name: CI
+
+on:
+  push:
+    branches: [ master ]
+  pull_request:
+    branches: [ master ]
+
+  # Allows you to run this workflow manually from the Actions tab
+  workflow_dispatch:
+
+jobs:
+  test:
+    name: mix test (Emacs ${{matrix.emacs_version}} | Elixir ${{matrix.elixir}} | Erlang/OTP ${{matrix.otp}})
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        emacs_version:
+          # Add more lines like this if you want to test on different Emacs versions.
+          - 27.1
+          - 26.3
+          - 26.1
+          - 25.2
+          - 25.1
+        include:
+          - elixir: 1.8.x
+            otp: 21.3.8.18
+          - elixir: 1.9.x
+            otp: 21.3.8.18
+          - elixir: 1.10.x
+            otp: 21.3.8.18
+          - elixir: 1.11.x
+            otp: 21.3.8.18
+          - elixir: 1.11.x
+            otp: 23.1.4
+    env:
+      MIX_ENV: test
+      ERT_RUNNER_ARGS:
+
+    steps:
+    - name: Set up Emacs
+      uses: purcell/setup-emacs@master
+      with:
+        version: ${{matrix.emacs_version}}
+
+    - name: Install Eldev
+      run: curl -fsSL https://raw.github.com/doublep/eldev/master/webinstall/github-eldev | sh
+
+    - name: Check out the source code
+      uses: actions/checkout@v2
+
+    - name: Test the project
+      run: |
+        eldev prepare
+        eldev -p -dtT test
diff --git a/.gitignore b/.gitignore
index 8b647d60..184d485f 100644
--- a/.gitignore
+++ b/.gitignore
@@ -3,3 +3,7 @@
 /.cask/
 /dist/
 *-emacs-elixir-format.ex
+
+# Added automatically by `eldev init'.
+/.eldev
+/Eldev-local
diff --git a/Eldev b/Eldev
new file mode 100644
index 00000000..bdeb0a00
--- /dev/null
+++ b/Eldev
@@ -0,0 +1,6 @@
+; -*- mode: emacs-lisp; lexical-binding: t; no-byte-compile: t -*-
+
+;; Autodetermined by `eldev init'.
+(eldev-use-package-archive 'melpa)
+
+(eldev-use-plugin 'autoloads)
diff --git a/elixir-mode.el b/elixir-mode.el
index 66a101ac..66eba09d 100644
--- a/elixir-mode.el
+++ b/elixir-mode.el
@@ -11,7 +11,7 @@
 ;; Created: Mon Nov 7 2011
 ;; Keywords: languages elixir
 ;; Version: 2.4.0
-;; Package-Requires: ((emacs "24") (pkg-info "0.4"))
+;; Package-Requires: ((emacs "24") (pkg-info "0.4") (s "1.2.0"))
 
 ;; This file is not a part of GNU Emacs.
 
diff --git a/test/elixir-mode-indentation-test.el b/test/elixir-mode-indentation-test.el
index 05d1751a..d0089f7f 100644
--- a/test/elixir-mode-indentation-test.el
+++ b/test/elixir-mode-indentation-test.el
@@ -9,6 +9,8 @@
 
 ;;; Code:
 
+(require 'test/test-helper)
+
 (elixir-def-indentation-test indent-use-dot-module-newline
                              (:tags '(indentation))
 "
diff --git a/test/test-helper.el b/test/test-helper.el
index d108e721..36ef5480 100644
--- a/test/test-helper.el
+++ b/test/test-helper.el
@@ -7,6 +7,7 @@
 
 (require 'ert-x)          ; `ert-with-test-buffer'
 (require 'cl-lib)         ; `cl-defmacro'
+(require 's)
 
 (message "Running tests on Emacs %s" emacs-version)