diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index 583db8c..3402b82 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -18,10 +18,9 @@ jobs:
           # Python versions (CPython):
           # https://raw.githubusercontent.com/actions/python-versions/main/versions-manifest.json
           #
-          # Python 3.7 is tested on Ubuntu 22.04 (below).
           # Python 3.6 is tested on Windows (below).
-          - "3.8"
-          - "3.9"
+          # Python 3.7 is tested on Ubuntu 22.04 (below).
+          # Python 3.8 and 3.9 are tested on Ubuntu 24.04 (below).
           - "3.10"
           - "3.11"
           - "3.12"
@@ -31,6 +30,8 @@ jobs:
           - "3.14t"
           - "3.15"
           - "3.15t"
+          - "3.16"
+          - "3.16t"
 
           # PyPy versions:
           # - https://github.com/actions/setup-python/blob/main/docs/advanced-usage.md
@@ -102,11 +103,13 @@ jobs:
           - os: macos-latest
             python: "3.15t"
 
-          # Ubuntu: test deadsnakes Python versions which are not supported by
-          # GHA python-versions.
-          # https://launchpad.net/~deadsnakes/+archive/ubuntu/ppa
+          # Old Python versions are only available on old Ubuntu versions
           - os: ubuntu-22.04
             python: "3.7"
+          - os: ubuntu-24.04
+            python: "3.8"
+          - os: ubuntu-24.04
+            python: "3.9"
 
     steps:
         # https://github.com/actions/checkout