diff --git a/test/conftest.py b/test/conftest.py
index 938ee2d1..e050fe6e 100644
--- a/test/conftest.py
+++ b/test/conftest.py
@@ -179,7 +179,7 @@ def test_json(tmp_path):
 
 @pytest.fixture
 def test_yaml(tmp_path):
-    test_yaml = yaml.dump({"foo": "bar"})
+    test_yaml = yaml.dump({"foo": "bar"}, encoding='utf-8')
     test_file = tmp_path / "test.txt"
     test_file.write_bytes(test_yaml)
     return test_file
@@ -189,7 +189,7 @@ def test_yaml(tmp_path):
 def test_toml(tmp_path):
     test_toml = toml.dumps({"foo": "bar"})
     test_file = tmp_path / "test.txt"
-    test_file.write_bytes(str(test_toml))
+    test_file.write_bytes(test_toml.encode('utf-8'))
     return test_file
 
 
@@ -198,14 +198,14 @@ def test_ldif(tmp_path):
     test_file = tmp_path / "test.txt"
     from ldif import LDIFWriter
 
-    writer = LDIFWriter(open(str(test_file), "wb"))
+    writer = LDIFWriter(open(str(test_file), "w"))
 
     writer.unparse(
         "mail=alice@example.com",
         {
-            "cn": ["Alice Alison"],
-            "mail": ["alice@example.com"],
-            "objectclass": ["top", "person"],
+            "cn": [b"Alice Alison"],
+            "mail": [b"alice@example.com"],
+            "objectclass": [b"top", b"person"],
         },
     )
 
diff --git a/test/test_filesystem.py b/test/test_filesystem.py
index 0974e837..698007af 100644
--- a/test/test_filesystem.py
+++ b/test/test_filesystem.py
@@ -121,16 +121,16 @@ def test_read_ldif(test_ldif):
     dn, entry = read_ldif(str(test_ldif))[0]
 
     assert dn == "mail=alice@example.com"
-    assert entry["mail"] == ["alice@example.com"]
-    assert entry["objectclass"] == ["top", "person"]
-    assert entry["cn"] == ["Alice Alison"]
+    assert entry["mail"] == [b"alice@example.com"]
+    assert entry["objectclass"] == [b"top", b"person"]
+    assert entry["cn"] == [b"Alice Alison"]
 
     dn, entry = read_ldif(str(test_ldif), ["objectclass"])[0]
 
     assert dn == "mail=alice@example.com"
-    assert entry["mail"] == ["alice@example.com"]
+    assert entry["mail"] == [b"alice@example.com"]
     assert "objectclass" not in entry
-    assert entry["cn"] == ["Alice Alison"]
+    assert entry["cn"] == [b"Alice Alison"]
 
 
 def test_read_ldif_cannot_ioerror(test_ldif, mocker):
@@ -465,10 +465,9 @@ def test_chown_exception(test_file, mocker):
         chown(str(test_file), 1)
 
     translation = m18n.g(
-        "error_changing_file_permissions", path=test_file, error=str(error)
+        "error_changing_file_permissions", path=str(test_file), error=str(error)
     )
-    expected_msg = translation.format(path=test_file, error=str(error))
-    assert expected_msg in str(exception)
+    assert translation in str(exception)
 
 
 def test_chmod(test_file):
@@ -504,10 +503,9 @@ def test_chmod_exception(test_file, mocker):
         chmod(str(test_file), 0o000)
 
     translation = m18n.g(
-        "error_changing_file_permissions", path=test_file, error=str(error)
+        "error_changing_file_permissions", path=str(test_file), error=str(error)
     )
-    expected_msg = translation.format(path=test_file, error=str(error))
-    assert expected_msg in str(exception)
+    assert translation in str(exception)
 
 
 def test_remove_file(test_file):