diff --git a/.github/workflows/run_tests.yml b/.github/workflows/run_tests.yml
index d35a63a..1e63bf2 100644
--- a/.github/workflows/run_tests.yml
+++ b/.github/workflows/run_tests.yml
@@ -16,9 +16,9 @@ jobs:
       - uses: actions/checkout@v2
       
       - name: Set up Python 3.5.3
-        uses: actions/setup-python@v2
+        uses: gabrielfalcao/pyenv-action@v7
         with:
-          python-version: '3.5.3'  # Debian Buster (stable)
+          default: '3.5.3'  # Debian Buster (stable)
       
       - name: Run Python unittests
         run: python3 -m unittest