diff --git a/setup.cfg b/setup.cfg
index fd87eac46..adbdfb11a 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -2,7 +2,7 @@
 # For details: https://github.com/nedbat/coveragepy/blob/master/NOTICE.txt
 
 [tool:pytest]
-addopts = -q -n auto --strict-markers --no-flaky-report -rfEX --failed-first
+addopts = -q -n auto -p no:legacypath --strict-markers --no-flaky-report -rfEX --failed-first
 python_classes = *Test
 markers =
     expensive: too slow to run during "make smoke"
diff --git a/tests/balance_xdist_plugin.py b/tests/balance_xdist_plugin.py
index 170037e6b..aec7dc21c 100644
--- a/tests/balance_xdist_plugin.py
+++ b/tests/balance_xdist_plugin.py
@@ -29,6 +29,7 @@
 import os
 import shutil
 import time
+
 from pathlib import Path
 
 import pytest
@@ -64,7 +65,7 @@ def pytest_sessionstart(self, session):
         if not self.running_all:
             return
 
-        tests_csv_dir = Path(session.startdir).resolve() / "tmp/tests_csv"
+        tests_csv_dir = session.startpath.resolve() / "tmp/tests_csv"
         self.tests_csv = tests_csv_dir / f"{self.worker}.csv"
 
         if self.worker == "none":
diff --git a/tests/mixins.py b/tests/mixins.py
index 7f2462998..0f578637d 100644
--- a/tests/mixins.py
+++ b/tests/mixins.py
@@ -12,7 +12,7 @@
 import os.path
 import sys
 
-from typing import Tuple
+from typing import Iterator, Tuple
 
 import pytest
 
@@ -57,10 +57,10 @@ class TempDirMixin:
     run_in_temp_dir = True
 
     @pytest.fixture(autouse=True)
-    def _temp_dir(self, tmpdir_factory):
+    def _temp_dir(self, tmp_path_factory: pytest.TempPathFactory) -> Iterator[None]:
         """Create a temp dir for the tests, if they want it."""
         if self.run_in_temp_dir:
-            tmpdir = tmpdir_factory.mktemp("t")
+            tmpdir = tmp_path_factory.mktemp("t")
             self.temp_dir = str(tmpdir)
             with change_dir(self.temp_dir):
                 # Modules should be importable from this temp directory.  We don't
diff --git a/tests/test_concurrency.py b/tests/test_concurrency.py
index b021d638b..d08ed1efb 100644
--- a/tests/test_concurrency.py
+++ b/tests/test_concurrency.py
@@ -6,6 +6,7 @@
 import glob
 import multiprocessing
 import os
+import pathlib
 import random
 import re
 import sys
@@ -626,21 +627,22 @@ def run_thread():           # pragma: nested
     assert has_stopped_coverage == [t.ident]
 
 
-def test_thread_safe_save_data(tmpdir):
+def test_thread_safe_save_data(tmp_path: pathlib.Path) -> None:
     # Non-regression test for: https://github.com/nedbat/coveragepy/issues/581
 
     # Create some Python modules and put them in the path
-    modules_dir = tmpdir.mkdir('test_modules')
+    modules_dir = tmp_path / "test_modules"
+    modules_dir.mkdir()
     module_names = [f"m{i:03d}" for i in range(1000)]
     for module_name in module_names:
-        modules_dir.join(module_name + ".py").write("def f(): pass\n")
+        (modules_dir / (module_name + ".py")).write_text("def f(): pass\n")
 
     # Shared variables for threads
     should_run = [True]
     imported = []
 
     old_dir = os.getcwd()
-    os.chdir(modules_dir.strpath)
+    os.chdir(modules_dir)
     try:
         # Make sure that all dummy modules can be imported.
         for module_name in module_names:
diff --git a/tests/test_python.py b/tests/test_python.py
index fd8e7b523..c8c58f4ef 100644
--- a/tests/test_python.py
+++ b/tests/test_python.py
@@ -3,6 +3,7 @@
 
 """Tests of coverage/python.py"""
 
+import pathlib
 import sys
 
 import pytest
@@ -37,9 +38,8 @@ def test_get_encoded_zip_files(self, encoding):
         assert mod.encoding == encoding
 
 
-def test_source_for_file(tmpdir):
-    path = tmpdir.join("a.py")
-    src = str(path)
+def test_source_for_file(tmp_path: pathlib.Path) -> None:
+    src = str(tmp_path / "a.py")
     assert source_for_file(src) == src
     assert source_for_file(src + 'c') == src
     assert source_for_file(src + 'o') == src
@@ -48,14 +48,15 @@ def test_source_for_file(tmpdir):
 
 
 @pytest.mark.skipif(not env.WINDOWS, reason="not windows")
-def test_source_for_file_windows(tmpdir):
-    path = tmpdir.join("a.py")
-    src = str(path)
+def test_source_for_file_windows(tmp_path: pathlib.Path) -> None:
+    a_py = tmp_path / "a.py"
+    src = str(a_py)
 
     # On windows if a pyw exists, it is an acceptable source
-    path_windows = tmpdir.ensure("a.pyw")
+    path_windows = tmp_path / "a.pyw"
+    path_windows.write_text("")
     assert str(path_windows) == source_for_file(src + 'c')
 
     # If both pyw and py exist, py is preferred
-    path.ensure(file=True)
+    a_py.write_text("")
     assert source_for_file(src + 'c') == src