diff --git a/.github/workflows/_test.yml b/.github/workflows/_test.yml
index 128fb8ad..f34f347d 100644
--- a/.github/workflows/_test.yml
+++ b/.github/workflows/_test.yml
@@ -14,10 +14,10 @@ jobs:
       - name: Checkout TUF
         uses: actions/checkout@8ade135a41bc03ea155e62e844d188df1ea18608 # v4.1.0
 
-      - name: Set up Python 3.x
+      - name: Set up Python (oldest supported version)
         uses: actions/setup-python@65d7f2d534ac1bc67fcd62888c5f4f3d2cb2b236 # v4.7.1
         with:
-          python-version: 3.x
+          python-version: 3.8
           cache: 'pip'
           cache-dependency-path: 'requirements/*.txt'