diff --git a/setup.py b/setup.py
index ad32d3f3..2ceaa359 100644
--- a/setup.py
+++ b/setup.py
@@ -14,7 +14,7 @@ extras = {
         "pytest-timeout",
         "pytest-xdist",
         "build",
-        "toml",
+        "toml_w",
     ],
     "bin": [
         "click",
diff --git a/unit_test/oci_container_test.py b/unit_test/oci_container_test.py
index baee3c3d..838c72bd 100644
--- a/unit_test/oci_container_test.py
+++ b/unit_test/oci_container_test.py
@@ -7,7 +7,8 @@ import textwrap
 from pathlib import Path, PurePath, PurePosixPath
 
 import pytest
-import toml
+
+import tomli_w
 
 from cibuildwheel.environment import EnvironmentAssignmentBash
 from cibuildwheel.oci_container import OCIContainer
@@ -269,11 +270,11 @@ def test_podman_vfs(tmp_path: Path, monkeypatch, request):
 
     vfs_containers_conf_fpath = vfs_path / "temp_vfs_containers.conf"
     vfs_containers_storage_conf_fpath = vfs_path / "temp_vfs_containers_storage.conf"
-    with open(vfs_containers_conf_fpath, "w") as file:
-        toml.dump(vfs_containers_conf_data, file)
+    with open(vfs_containers_conf_fpath, "wb") as file:
+        tomli_w.dump(vfs_containers_conf_data, file)
 
-    with open(vfs_containers_storage_conf_fpath, "w") as file:
-        toml.dump(vfs_containers_storage_conf_data, file)
+    with open(vfs_containers_storage_conf_fpath, "wb") as file:
+        tomli_w.dump(vfs_containers_storage_conf_data, file)
 
     monkeypatch.setenv("CONTAINERS_CONF", str(vfs_containers_conf_fpath))
     monkeypatch.setenv("CONTAINERS_STORAGE_CONF", str(vfs_containers_storage_conf_fpath))