diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 5194fbe..11aee65 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -22,6 +22,13 @@ jobs:
       matrix:
         os: [ubuntu-latest, macos-15-intel]
         python: ['3.9', '3.12']
+        # Python 3.9 has no setup-python build for Ubuntu 26.04.
+        exclude:
+          - os: ubuntu-latest
+            python: '3.9'
+        include:
+          - os: ubuntu-24.04
+            python: '3.9'
     env:
       PYTHONDONTWRITEBYTECODE: '1'
     steps: