diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 853bda3..b590d55 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -11,53 +11,108 @@ jobs:
   mix_test_old:
     name: mix test (Elixir ${{matrix.elixir}} | OTP ${{matrix.otp}})
     runs-on: ${{ matrix.os }}
+    strategy:
+      fail-fast: false
+      matrix:
+        include:
+          - elixir: 1.13.x
+            otp: 24
+            os: ubuntu-22.04
+            gcc: gcc-10
+            gpp: g++-10
+          - elixir: 1.14.x
+            otp: 25
+            os: ubuntu-22.04
+            gcc: gcc-11
+            gpp: g++-11
+          - elixir: 1.15.x
+            otp: 26
+            os: ubuntu-22.04
+            gcc: gcc-11
+            gpp: g++-11
+          - elixir: 1.16.x
+            otp: 26
+            os: ubuntu-22.04
+            gcc: gcc-11
+            gpp: g++-11
+          - elixir: 1.17.x
+            otp: 27
+            os: ubuntu-24.04
+            gcc: gcc-13
+            gpp: g++-13
+          - elixir: 1.18.x
+            otp: 27
+            os: ubuntu-latest
+            gcc: gcc-13
+            gpp: g++-13
+            warnings_as_errors: true
+    env:
+      MIX_ENV: test
+    steps:
+      - uses: actions/checkout@v2
+      - uses: erlef/setup-beam@v1
+        with:
+          otp-version: ${{matrix.otp}}
+          elixir-version: ${{matrix.elixir}}
+      - name: Install Dependencies
+        run: |
+          mix local.hex --force
+          mix local.rebar --force
+          mix deps.get --only test
+      - name: Cache build artifacts
+        uses: actions/cache@v3
+        with:
+          path: |
+            ~/.hex
+            ~/.mix
+            _build
+          key: ${{ matrix.otp }}-${{ matrix.elixir }}-build
+      - run: mix compile --warnings-as-errors
+        if: matrix.warnings_as_errors
+        env:
+          CC: ${{matrix.gcc}}
+          CXX: ${{matrix.gpp}}
+      - run: mix test
+        env:
+          CC: ${{matrix.gcc}}
+          CXX: ${{matrix.gpp}}
+  mix_test_even_older:
+    name: mix test (Elixir ${{matrix.elixir}} | OTP ${{matrix.otp}})
+    runs-on: ubuntu-latest
+    container:
+      image: ubuntu:focal-20250404
+      env:
+        ImageOS: ubuntu20
+        MIX_ENV: test
     strategy:
       fail-fast: false
       matrix:
         include:
           - elixir: 1.4.x
             otp: 20
-            os: ubuntu-20.04
           - elixir: 1.5.x
             otp: 20
-            os: ubuntu-20.04
           - elixir: 1.6.x
             otp: 20
-            os: ubuntu-20.04
           - elixir: 1.7.x
             otp: 20
-            os: ubuntu-20.04
           - elixir: 1.8.x
             otp: 20
-            os: ubuntu-20.04
           - elixir: 1.9.x
             otp: 20
-            os: ubuntu-20.04
           - elixir: 1.10.x
             otp: 21
-            os: ubuntu-20.04
           - elixir: 1.11.x
             otp: 22
-            os: ubuntu-20.04
           - elixir: 1.11.x
             otp: 23
-            os: ubuntu-20.04
           - elixir: 1.12.x
             otp: 23
-            os: ubuntu-20.04
-          - elixir: 1.13.x
-            otp: 24
-            os: ubuntu-20.04
-          - elixir: 1.14.x
-            otp: 25
-            os: ubuntu-22.04
-          - elixir: 1.15.x
-            otp: 26
-            os: ubuntu-latest
-            warnings_as_errors: true
-    env:
-      MIX_ENV: test
     steps:
+      # Needed by erlef/setup-beam action
+      - run: |
+          apt update -qqy
+          apt install -qqy build-essential libssl-dev unzip
       - uses: actions/checkout@v2
       - uses: erlef/setup-beam@v1
         with:
@@ -76,15 +131,11 @@ jobs:
             ~/.mix
             _build
           key: ${{ matrix.otp }}-${{ matrix.elixir }}-build
-      - run: mix compile --warnings-as-errors
-        if: matrix.warnings_as_errors
+      - run: mix compile
         env:
-          CC: gcc-10
-          CXX: g++-10
+          CC: gcc-9
+          CXX: g++-9
       - run: mix test
-        env:
-          CC: gcc-10
-          CXX: g++-10
   dialyzer:
     name: mix dialyzer
     runs-on: ubuntu-latest
@@ -94,8 +145,8 @@ jobs:
       - uses: actions/checkout@v2
       - uses: erlef/setup-beam@v1
         with:
-          otp-version: 26
-          elixir-version: 1.15.x
+          elixir-version: 1.18.x
+          otp-version: 27
       - name: Install Dependencies
         run: |
           mix local.hex --force