diff --git a/procrunner/__init__.py b/procrunner/__init__.py
index 231fecd..fba7bb9 100644
--- a/procrunner/__init__.py
+++ b/procrunner/__init__.py
@@ -273,7 +273,7 @@
     return obj
 
 
-def _windows_resolve(command):
+def _windows_resolve(command, path=None):
     """
     Try and find the full path and file extension of the executable to run.
     This is so that e.g. calls to 'somescript' will point at 'somescript.cmd'
@@ -288,7 +288,7 @@
     if not command or not isinstance(command[0], str):
         return command
 
-    found_executable = shutil.which(command[0])
+    found_executable = shutil.which(command[0], path=path)
     if found_executable:
         logger.debug("Resolved %s as %s", command[0], found_executable)
         return (found_executable, *command[1:])
@@ -297,7 +297,7 @@
         # Special case. shutil.which may not detect file extensions if a full
         # path is given, so try to resolve the executable explicitly
         for extension in os.getenv("PATHEXT").split(os.pathsep):
-            found_executable = shutil.which(command[0] + extension)
+            found_executable = shutil.which(command[0] + extension, path=path)
             if found_executable:
                 return (found_executable, *command[1:])
 
diff --git a/tests/test_procrunner_resolution.py b/tests/test_procrunner_resolution.py
index 2237c7c..e099be4 100644
--- a/tests/test_procrunner_resolution.py
+++ b/tests/test_procrunner_resolution.py
@@ -58,27 +58,25 @@
 
 
 @pytest.mark.skipif(sys.platform != "win32", reason="windows specific test only")
-def test_name_resolution_for_complex_cases(tmpdir):
-    tmpdir.chdir()
-
+def test_name_resolution_for_complex_cases(tmp_path):
     bat = "simple_bat_extension"
     cmd = "simple_cmd_extension"
     exe = "simple_exe_extension"
     dotshort = "more_complex_filename_with_a.dot"
     dotlong = "more_complex_filename.withadot"
 
-    (tmpdir / bat + ".bat").ensure()
-    (tmpdir / cmd + ".cmd").ensure()
-    (tmpdir / exe + ".exe").ensure()
-    (tmpdir / dotshort + ".bat").ensure()
-    (tmpdir / dotlong + ".cmd").ensure()
+    (tmp_path / (bat + ".bat")).touch()
+    (tmp_path / (cmd + ".cmd")).touch()
+    (tmp_path / (exe + ".exe")).touch()
+    (tmp_path / (dotshort + ".bat")).touch()
+    (tmp_path / (dotlong + ".cmd")).touch()
 
     def is_valid(command):
         assert len(command) == 1
-        assert os.path.exists(command[0])
+        assert os.path.exists(tmp_path / command[0])
 
-    is_valid(procrunner._windows_resolve([bat]))
-    is_valid(procrunner._windows_resolve([cmd]))
-    is_valid(procrunner._windows_resolve([exe]))
-    is_valid(procrunner._windows_resolve([dotshort]))
-    is_valid(procrunner._windows_resolve([dotlong]))
+    is_valid(procrunner._windows_resolve([bat], path=os.fspath(tmp_path)))
+    is_valid(procrunner._windows_resolve([cmd], path=os.fspath(tmp_path)))
+    is_valid(procrunner._windows_resolve([exe], path=os.fspath(tmp_path)))
+    is_valid(procrunner._windows_resolve([dotshort], path=os.fspath(tmp_path)))
+    is_valid(procrunner._windows_resolve([dotlong], path=os.fspath(tmp_path)))
diff --git a/tests/test_procrunner_system.py b/tests/test_procrunner_system.py
index cbd126d..a78db0c 100644
--- a/tests/test_procrunner_system.py
+++ b/tests/test_procrunner_system.py
@@ -40,11 +40,10 @@
     assert err == ""
 
 
-def test_running_wget(tmpdir):
-    tmpdir.chdir()
+def test_running_wget(tmp_path):
     command = ["wget", "https://www.google.com", "-O", "-"]
     try:
-        result = procrunner.run(command)
+        result = procrunner.run(command, working_directory=tmp_path)
     except OSError as e:
         if e.errno == 2:
             pytest.skip("wget not available")
@@ -54,15 +53,15 @@
     assert b"google" in result.stdout
 
 
-def test_path_object_resolution(tmpdir):
+def test_path_object_resolution(tmp_path):
     sentinel_value = b"sentinel"
-    tmpdir.join("tempfile").write(sentinel_value)
-    tmpdir.join("reader.py").write("print(open('tempfile').read())")
+    tmp_path.joinpath("tempfile").write_bytes(sentinel_value)
+    tmp_path.joinpath("reader.py").write_text("print(open('tempfile').read())")
     assert "LEAK_DETECTOR" not in os.environ
     result = procrunner.run(
-        [sys.executable, tmpdir.join("reader.py")],
+        [sys.executable, tmp_path / "reader.py"],
         environment_override={"PYTHONHASHSEED": "random", "LEAK_DETECTOR": "1"},
-        working_directory=tmpdir,
+        working_directory=tmp_path,
     )
     assert result.returncode == 0
     assert not result.stderr