diff --git a/.github/workflows/on-push.yml b/.github/workflows/on-push.yml
index e5b8211..938ef64 100644
--- a/.github/workflows/on-push.yml
+++ b/.github/workflows/on-push.yml
@@ -151,6 +151,8 @@ jobs:
         include:
         - python-version: '3.9'
           extra: -ci
+        - python-version: '3.12'
+          extra: -ci
         - python-version: '3.11'
           extra: -integration
 
diff --git a/tests/test_50_io_encoder.py b/tests/test_50_io_encoder.py
index 1ebf2cd..5d6b12c 100644
--- a/tests/test_50_io_encoder.py
+++ b/tests/test_50_io_encoder.py
@@ -173,7 +173,7 @@ def test_io_locker(
     fs.touch(file_path)
     fs.touch(f"{file_path}.lock")
 
-    process = subprocess.Popen(f"sleep 0.1; rm {file_path}.lock", shell=True)
+    process = subprocess.Popen(f"sleep 1; rm {file_path}.lock", shell=True)
     with raises_or_warns:
         cached_open(tmpfile)
     assert process.wait() == 0