diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
new file mode 100644
index 0000000..3ffc48b
--- /dev/null
+++ b/.github/workflows/ci.yml
@@ -0,0 +1,36 @@
+name: Elixir CI
+
+on:
+  pull_request:
+    branches: [master]
+
+jobs:
+  test:
+    name: Elixir ${{ matrix.elixir }} / OTP ${{ matrix.otp }}
+    runs-on: ubuntu-latest
+
+    strategy:
+      fail-fast: false
+      matrix:
+        elixir: ["1.18", "1.19"]
+        otp: ["27", "28"]
+
+    steps:
+      - uses: actions/checkout@v5
+
+      - uses: erlef/setup-beam@v1
+        with:
+          elixir-version: "${{ matrix.elixir }}"
+          otp-version: "${{ matrix.otp }}"
+
+      - name: Install dependencies
+        run: mix deps.get
+
+      - name: Compile with warnings as errors
+        run: mix compile --warnings-as-errors --force
+
+      - name: Check formatting
+        run: mix format --check-formatted
+
+      - name: Run tests
+        run: mix test
diff --git a/.tool-versions b/.tool-versions
index 36d48b8..b4fc3c7 100644
--- a/.tool-versions
+++ b/.tool-versions
@@ -1 +1,2 @@
-elixir 1.9.1
+erlang 27.3.4.6
+elixir 1.19.5-otp-27
diff --git a/config/config.exs b/config/config.exs
index 03495c0..0e067c1 100644
--- a/config/config.exs
+++ b/config/config.exs
@@ -1,6 +1,6 @@
 # This file is responsible for configuring your application
 # and its dependencies with the aid of the Mix.Config module.
-use Mix.Config
+import Config
 
 # This configuration is loaded before any dependency and is restricted
 # to this project. If another project depends on this project, this
diff --git a/mix.exs b/mix.exs
index 31a4322..3de80e9 100644
--- a/mix.exs
+++ b/mix.exs
@@ -31,8 +31,8 @@ defmodule HLClock.Mixfile do
 
   defp deps do
     [
-      {:stream_data, "~> 0.2", only: [:test, :dev]},
-      {:ex_doc, "~> 0.19", only: :dev}
+      {:stream_data, "~> 1.0", only: [:test, :dev]},
+      {:ex_doc, "~> 0.40", only: :dev}
     ]
   end
 
diff --git a/mix.lock b/mix.lock
index 46bddd3..aa4366b 100644
--- a/mix.lock
+++ b/mix.lock
@@ -1,6 +1,10 @@
-%{"earmark": {:hex, :earmark, "1.3.5", "0db71c8290b5bc81cb0101a2a507a76dca659513984d683119ee722828b424f6", [:mix], [], "hexpm"},
-  "ex_doc": {:hex, :ex_doc, "0.21.1", "5ac36660846967cd869255f4426467a11672fec3d8db602c429425ce5b613b90", [:mix], [{:earmark, "~> 1.3", [hex: :earmark, repo: "hexpm", optional: false]}, {:makeup_elixir, "~> 0.14", [hex: :makeup_elixir, repo: "hexpm", optional: false]}], "hexpm"},
-  "makeup": {:hex, :makeup, "1.0.0", "671df94cf5a594b739ce03b0d0316aa64312cee2574b6a44becb83cd90fb05dc", [:mix], [{:nimble_parsec, "~> 0.5.0", [hex: :nimble_parsec, repo: "hexpm", optional: false]}], "hexpm"},
-  "makeup_elixir": {:hex, :makeup_elixir, "0.14.0", "cf8b7c66ad1cff4c14679698d532f0b5d45a3968ffbcbfd590339cb57742f1ae", [:mix], [{:makeup, "~> 1.0", [hex: :makeup, repo: "hexpm", optional: false]}], "hexpm"},
-  "nimble_parsec": {:hex, :nimble_parsec, "0.5.1", "c90796ecee0289dbb5ad16d3ad06f957b0cd1199769641c961cfe0b97db190e0", [:mix], [], "hexpm"},
-  "stream_data": {:hex, :stream_data, "0.4.3", "62aafd870caff0849a5057a7ec270fad0eb86889f4d433b937d996de99e3db25", [:mix], [], "hexpm"}}
+%{
+  "earmark": {:hex, :earmark, "1.3.5", "0db71c8290b5bc81cb0101a2a507a76dca659513984d683119ee722828b424f6", [:mix], [], "hexpm", "762b999fd414fb41e297944228aa1de2cd4a3876a07f968c8b11d1e9a2190d07"},
+  "earmark_parser": {:hex, :earmark_parser, "1.4.44", "f20830dd6b5c77afe2b063777ddbbff09f9759396500cdbe7523efd58d7a339c", [:mix], [], "hexpm", "4778ac752b4701a5599215f7030989c989ffdc4f6df457c5f36938cc2d2a2750"},
+  "ex_doc": {:hex, :ex_doc, "0.40.2", "f50edec428c4b0a457a167de42414c461122a3585a99515a69d09fff19e5597e", [:mix], [{:earmark_parser, "~> 1.4.44", [hex: :earmark_parser, repo: "hexpm", optional: false]}, {:makeup_c, ">= 0.1.0", [hex: :makeup_c, repo: "hexpm", optional: true]}, {:makeup_elixir, "~> 0.14 or ~> 1.0", [hex: :makeup_elixir, repo: "hexpm", optional: false]}, {:makeup_erlang, "~> 0.1 or ~> 1.0", [hex: :makeup_erlang, repo: "hexpm", optional: false]}, {:makeup_html, ">= 0.1.0", [hex: :makeup_html, repo: "hexpm", optional: true]}], "hexpm", "4fa426e2beb47854a162e2c488727fdec51cd4692e319b23810c2804cb1a40fe"},
+  "makeup": {:hex, :makeup, "1.2.1", "e90ac1c65589ef354378def3ba19d401e739ee7ee06fb47f94c687016e3713d1", [:mix], [{:nimble_parsec, "~> 1.4", [hex: :nimble_parsec, repo: "hexpm", optional: false]}], "hexpm", "d36484867b0bae0fea568d10131197a4c2e47056a6fbe84922bf6ba71c8d17ce"},
+  "makeup_elixir": {:hex, :makeup_elixir, "1.0.1", "e928a4f984e795e41e3abd27bfc09f51db16ab8ba1aebdba2b3a575437efafc2", [:mix], [{:makeup, "~> 1.0", [hex: :makeup, repo: "hexpm", optional: false]}, {:nimble_parsec, "~> 1.2.3 or ~> 1.3", [hex: :nimble_parsec, repo: "hexpm", optional: false]}], "hexpm", "7284900d412a3e5cfd97fdaed4f5ed389b8f2b4cb49efc0eb3bd10e2febf9507"},
+  "makeup_erlang": {:hex, :makeup_erlang, "1.1.0", "835f7e60792e08824cda445639555d7bf1bbbddb1b60b306e33cb6f6db24dc74", [:mix], [{:makeup, "~> 1.0", [hex: :makeup, repo: "hexpm", optional: false]}], "hexpm", "1cd6780fb1dd1a03979abaed0fe82712b0625118fd5257d3ebbf73f960c73c3c"},
+  "nimble_parsec": {:hex, :nimble_parsec, "1.4.2", "8efba0122db06df95bfaa78f791344a89352ba04baedd3849593bfce4d0dc1c6", [:mix], [], "hexpm", "4b21398942dda052b403bbe1da991ccd03a053668d147d53fb8c4e0efe09c973"},
+  "stream_data": {:hex, :stream_data, "1.3.0", "bde37905530aff386dea1ddd86ecbf00e6642dc074ceffc10b7d4e41dfd6aac9", [:mix], [], "hexpm", "3cc552e286e817dca43c98044c706eec9318083a1480c52ae2688b08e2936e3c"},
+}