diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index a00a481..88d032f 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -8,8 +8,7 @@ on:
 
 jobs:
   test:
-    name: Elixir ${{matrix.elixir}} / OTP ${{matrix.otp}}
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-20.04
 
     services:
       postgres:
@@ -21,23 +20,26 @@ jobs:
           POSTGRES_PASSWORD: postgres
 
     strategy:
+      fail-fast: false
       matrix:
-        elixir:
-          - '1.13'
-          - '1.14'
-        otp:
-          - '24'
-          - '25'
+        include:
+          - pair:
+              elixir: 1.11.4
+              otp: 22.3
+          - pair:
+              elixir: 1.15.7
+              otp: 26.1
+            lint: lint
 
     steps:
     - name: Checkout
-      uses: actions/checkout@v3
+      uses: actions/checkout@v4
 
     - name: Set up Elixir
       uses: erlef/setup-beam@v1
       with:
-        elixir-version: ${{ matrix.elixir }}
-        otp-version: ${{ matrix.otp }}
+        elixir-version: ${{ matrix.pair.elixir }}
+        otp-version: ${{ matrix.pair.otp }}
 
     - name: Restore deps cache
       uses: actions/cache@v3
@@ -45,10 +47,10 @@ jobs:
         path: |
           deps
           _build
-        key: deps-${{ runner.os }}-${{ matrix.otp }}-${{ matrix.elixir }}-${{ hashFiles('**/mix.lock') }}-git-${{ github.sha }}
+        key: deps-${{ runner.os }}-${{ matrix.pair.otp }}-${{ matrix.pair.elixir }}-${{ hashFiles('**/mix.lock') }}-git-${{ github.sha }}
         restore-keys: |
-          deps-${{ runner.os }}-${{ matrix.otp }}-${{ matrix.elixir }}-${{ hashFiles('**/mix.lock') }}
-          deps-${{ runner.os }}-${{ matrix.otp }}-${{ matrix.elixir }}
+          deps-${{ runner.os }}-${{ matrix.pair.otp }}-${{ matrix.pair.elixir }}-${{ hashFiles('**/mix.lock') }}
+          deps-${{ runner.os }}-${{ matrix.pair.otp }}-${{ matrix.pair.elixir }}
 
     - name: Create dializer plts path
       run: mkdir -p priv/plts
@@ -57,21 +59,32 @@ jobs:
       uses: actions/cache@v3
       with:
         path: priv/plts
-        key: plts-${{ runner.os }}-${{ matrix.otp }}-${{ matrix.elixir }}-${{ hashFiles('**/mix.lock') }}-${{ github.sha }}
+        key: plts-${{ runner.os }}-${{ matrix.pair.otp }}-${{ matrix.pair.elixir }}-${{ hashFiles('**/mix.lock') }}-${{ github.sha }}
         restore-keys: |
-          plts-${{ runner.os }}-${{ matrix.otp }}-${{ matrix.elixir }}-${{ hashFiles('**/mix.lock') }}
-          plts-${{ runner.os }}-${{ matrix.otp }}-${{ matrix.elixir }}
+          plts-${{ runner.os }}-${{ matrix.pair.otp }}-${{ matrix.pair.elixir }}-${{ hashFiles('**/mix.lock') }}
+          plts-${{ runner.os }}-${{ matrix.pair.otp }}-${{ matrix.pair.elixir }}
 
     - name: Install package dependencies
       run: mix deps.get
 
     - name: Check code format
       run: mix format --check-formatted
+      if: ${{ matrix.lint }}
+
+    - name: Check unused deps
+      run: mix deps.unlock --check-unused
+      if: ${{ matrix.lint }}
 
     - name: Compile dependencies
-      run: mix compile
+      run: mix deps.compile
+      env:
+        MIX_ENV: test
+
+    - name: Compile app
+      run: mix compile --warnings-as-errors
       env:
         MIX_ENV: test
+      if: ${{ matrix.lint }}
 
     - name: Run unit tests
       run: |
@@ -82,3 +95,4 @@ jobs:
 
     - name: Run dialyzer
       run: mix dialyzer
+      if: ${{ matrix.lint }}
diff --git a/.tool-versions b/.tool-versions
index ffcdf14..510eaf4 100644
--- a/.tool-versions
+++ b/.tool-versions
@@ -1,2 +1,2 @@
-elixir 1.14.1-otp-24 1.12.0-otp-24
-erlang 24.1.7 24.1.5 24.1.2 24.1.1 24.0
+elixir 1.15.7-otp-26
+erlang 26.1.2
diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index 3394e13..5473522 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -17,7 +17,7 @@ Make sure the tests pass.
 
 Running tests for Dataloader requires a running instance of Postgres. The easiest way to do this is to run Postgres inside of Docker whilst running the Dataloader tests. In one terminal run:
 
-    docker run -p 5432:5432 -e POSTGRES_PASSWORD=postgres -e POSTGRES_DB=dataloader_test postgres
+    docker run -p 5432:5432 -e POSTGRES_PASSWORD=postgres -e POSTGRES_DB=dataloader_test docker.io/postgres
 
 and in another terminal run:
 
diff --git a/lib/dataloader.ex b/lib/dataloader.ex
index 28a47c7..1082d15 100644
--- a/lib/dataloader.ex
+++ b/lib/dataloader.ex
@@ -394,13 +394,13 @@ defmodule Dataloader do
   # Optionally use `async/1` and `async_stream/3` functions from
   # `opentelemetry_process_propagator` if available
   if Code.ensure_loaded?(OpentelemetryProcessPropagator.Task) do
-    @spec async((() -> any)) :: Task.t()
+    @spec async((-> any)) :: Task.t()
     defdelegate async(fun), to: OpentelemetryProcessPropagator.Task
 
     @spec async_stream(Enumerable.t(), (term -> term), keyword) :: Enumerable.t()
     defdelegate async_stream(items, fun, opts), to: OpentelemetryProcessPropagator.Task
   else
-    @spec async((() -> any)) :: Task.t()
+    @spec async((-> any)) :: Task.t()
     defdelegate async(fun), to: Task
 
     @spec async_stream(Enumerable.t(), (term -> term), keyword) :: Enumerable.t()
diff --git a/mix.exs b/mix.exs
index b964f68..a34bc10 100644
--- a/mix.exs
+++ b/mix.exs
@@ -8,7 +8,7 @@ defmodule Dataloader.Mixfile do
     [
       app: :dataloader,
       version: @version,
-      elixir: "~> 1.12",
+      elixir: "~> 1.11",
       start_permanent: Mix.env() == :prod,
       elixirc_paths: elixirc_paths(Mix.env()),
       package: package(),
diff --git a/mix.lock b/mix.lock
index 2c195ff..a0f6cec 100644
--- a/mix.lock
+++ b/mix.lock
@@ -1,5 +1,4 @@
 %{
-  "connection": {:hex, :connection, "1.1.0", "ff2a49c4b75b6fb3e674bfc5536451607270aac754ffd1bdfe175abe4a6d7a68", [:mix], [], "hexpm", "722c1eb0a418fbe91ba7bd59a47e28008a189d47e37e0e7bb85585a016b2869c"},
   "db_connection": {:hex, :db_connection, "2.5.0", "bb6d4f30d35ded97b29fe80d8bd6f928a1912ca1ff110831edcd238a1973652c", [:mix], [{:telemetry, "~> 0.4 or ~> 1.0", [hex: :telemetry, repo: "hexpm", optional: false]}], "hexpm", "c92d5ba26cd69ead1ff7582dbb860adeedfff39774105a4f1c92cbb654b55aa2"},
   "decimal": {:hex, :decimal, "2.1.1", "5611dca5d4b2c3dd497dec8f68751f1f1a54755e8ed2a966c2633cf885973ad6", [:mix], [], "hexpm", "53cfe5f497ed0e7771ae1a475575603d77425099ba5faef9394932b35020ffcc"},
   "dialyxir": {:hex, :dialyxir, "1.3.0", "fd1672f0922b7648ff9ce7b1b26fcf0ef56dda964a459892ad15f6b4410b5284", [:mix], [{:erlex, ">= 0.2.6", [hex: :erlex, repo: "hexpm", optional: false]}], "hexpm", "00b2a4bcd6aa8db9dcb0b38c1225b7277dca9bc370b6438715667071a304696f"},