diff --git a/.github/workflows/run-installation-tests.yaml b/.github/workflows/run-installation-tests.yaml
index c3c8fd5..b1d39c7 100644
--- a/.github/workflows/run-installation-tests.yaml
+++ b/.github/workflows/run-installation-tests.yaml
@@ -6,7 +6,7 @@ jobs:
   test:
     runs-on: ubuntu-latest
     container:
-      image: davhofer/py2spack-spack-installation-test:latest
+      image: davhofer/py2spack-spack-installation-test-py3.9:latest
 
     steps:
       - name: Checkout code
diff --git a/.github/workflows/run-pytest.yaml b/.github/workflows/run-pytest.yaml
index ef91321..071c345 100644
--- a/.github/workflows/run-pytest.yaml
+++ b/.github/workflows/run-pytest.yaml
@@ -6,7 +6,7 @@ jobs:
   test:
     runs-on: ubuntu-latest
     container:
-      image: davhofer/py2spack-spack-installation-test:latest 
+      image: davhofer/py2spack-spack-installation-test-py3.9:latest
 
     steps:
       - name: Checkout code
diff --git a/Dockerfile b/Dockerfile
index 6cd8b69..2f768c9 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,4 +1,4 @@
-FROM python:3.12
+FROM python:3.9
 
 # Install system dependencies
 RUN apt-get update && \
diff --git a/src/py2spack/package_providers.py b/src/py2spack/package_providers.py
index d4ba4b0..8684937 100644
--- a/src/py2spack/package_providers.py
+++ b/src/py2spack/package_providers.py
@@ -6,10 +6,9 @@
 import dataclasses
 import functools
 import hashlib
-import io
 import re
 from collections.abc import Hashable
-from typing import Protocol
+from typing import TYPE_CHECKING, Protocol
 
 import requests
 from packaging import version as vn
@@ -17,6 +16,10 @@
 from py2spack import utils
 
 
+if TYPE_CHECKING:
+    import io
+
+
 TARBALL_ARCHIVE_FORMATS = [
     ".tar",
     ".tar.gz",