diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index a8cab77..89a034e 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -38,7 +38,7 @@ jobs:
       run: |
         toxenv=$(python -c '
         ver=r"${{ matrix.python }}".replace(".", "")
-        print(f"py{ver}" if ver[0].isdigit() else ver)
+        print("py" + ver if ver[0].isdigit() else ver)
         ')
         echo toxenv is "$toxenv";
         echo "TOXENV=$toxenv" >> "$GITHUB_ENV"