diff --git a/pre_commit/languages/conda.py b/pre_commit/languages/conda.py
index 05f1d291..41c355e7 100644
--- a/pre_commit/languages/conda.py
+++ b/pre_commit/languages/conda.py
@@ -2,6 +2,7 @@ from __future__ import annotations
 
 import contextlib
 import os
+import sys
 from typing import Generator
 from typing import Sequence
 
@@ -26,7 +27,7 @@ def get_env_patch(env: str) -> PatchesT:
     # $CONDA_PREFIX/Scripts and $CONDA_PREFIX. Whereas the latter only
     # seems to be used for python.exe.
     path: SubstitutionT = (os.path.join(env, 'bin'), os.pathsep, Var('PATH'))
-    if os.name == 'nt':  # pragma: no cover (platform specific)
+    if sys.platform == 'win32':  # pragma: win32 cover
         path = (env, os.pathsep, *path)
         path = (os.path.join(env, 'Scripts'), os.pathsep, *path)
         path = (os.path.join(env, 'Library', 'bin'), os.pathsep, *path)
diff --git a/pre_commit/languages/python.py b/pre_commit/languages/python.py
index 976674e2..3ef34360 100644
--- a/pre_commit/languages/python.py
+++ b/pre_commit/languages/python.py
@@ -48,7 +48,7 @@ def _read_pyvenv_cfg(filename: str) -> dict[str, str]:
 
 def bin_dir(venv: str) -> str:
     """On windows there's a different directory for the virtualenv"""
-    bin_part = 'Scripts' if os.name == 'nt' else 'bin'
+    bin_part = 'Scripts' if sys.platform == 'win32' else 'bin'
     return os.path.join(venv, bin_part)
 
 
@@ -137,7 +137,7 @@ def norm_version(version: str) -> str | None:
     elif _sys_executable_matches(version):  # virtualenv defaults to our exe
         return None
 
-    if os.name == 'nt':  # pragma: no cover (windows)
+    if sys.platform == 'win32':  # pragma: no cover (windows)
         version_exec = _find_by_py_launcher(version)
         if version_exec:
             return version_exec
diff --git a/pre_commit/util.py b/pre_commit/util.py
index ea0d4f52..4f8e8357 100644
--- a/pre_commit/util.py
+++ b/pre_commit/util.py
@@ -119,7 +119,7 @@ def cmd_output(*cmd: str, **kwargs: Any) -> tuple[int, str, str | None]:
     return returncode, stdout, stderr
 
 
-if os.name != 'nt':  # pragma: win32 no cover
+if sys.platform != 'win32':  # pragma: win32 no cover
     from os import openpty
     import termios
 
diff --git a/testing/util.py b/testing/util.py
index 7c68d0ee..0fee2826 100644
--- a/testing/util.py
+++ b/testing/util.py
@@ -3,6 +3,7 @@ from __future__ import annotations
 import contextlib
 import os.path
 import subprocess
+import sys
 
 import pytest
 
@@ -30,7 +31,7 @@ def cmd_output_mocked_pre_commit_home(
     return ret, out.replace('\r\n', '\n'), None
 
 
-xfailif_windows = pytest.mark.xfail(os.name == 'nt', reason='windows')
+xfailif_windows = pytest.mark.xfail(sys.platform == 'win32', reason='windows')
 
 
 def run_opts(
diff --git a/tests/languages/python_test.py b/tests/languages/python_test.py
index 8bb284eb..a4000b41 100644
--- a/tests/languages/python_test.py
+++ b/tests/languages/python_test.py
@@ -36,10 +36,10 @@ def test_read_pyvenv_cfg_non_utf8(tmpdir):
 
 def test_norm_version_expanduser():
     home = os.path.expanduser('~')
-    if os.name == 'nt':  # pragma: nt cover
+    if sys.platform == 'win32':  # pragma: win32 cover
         path = r'~\python343'
         expected_path = fr'{home}\python343'
-    else:  # pragma: nt no cover
+    else:  # pragma: win32 no cover
         path = '~/.pyenv/versions/3.4.3/bin/python'
         expected_path = f'{home}/.pyenv/versions/3.4.3/bin/python'
     result = python.norm_version(path)
diff --git a/tests/parse_shebang_test.py b/tests/parse_shebang_test.py
index 2fcb29ee..dd97ca5d 100644
--- a/tests/parse_shebang_test.py
+++ b/tests/parse_shebang_test.py
@@ -94,7 +94,7 @@ def test_normexe_does_not_exist_sep():
     assert excinfo.value.args == ('Executable `./i-dont-exist-lol` not found',)
 
 
-@pytest.mark.xfail(os.name == 'nt', reason='posix only')
+@pytest.mark.xfail(sys.platform == 'win32', reason='posix only')
 def test_normexe_not_executable(tmpdir):  # pragma: win32 no cover
     tmpdir.join('exe').ensure()
     with tmpdir.as_cwd(), pytest.raises(OSError) as excinfo:
diff --git a/tests/repository_test.py b/tests/repository_test.py
index 9e5d9d62..8fe6e02b 100644
--- a/tests/repository_test.py
+++ b/tests/repository_test.py
@@ -2,6 +2,7 @@ from __future__ import annotations
 
 import os.path
 import shutil
+import sys
 from typing import Any
 from unittest import mock
 
@@ -198,7 +199,7 @@ def test_intermixed_stdout_stderr(tempdir_factory, store):
     )
 
 
-@pytest.mark.xfail(os.name == 'nt', reason='ptys are posix-only')
+@pytest.mark.xfail(sys.platform == 'win32', reason='ptys are posix-only')
 def test_output_isatty(tempdir_factory, store):
     _test_hook_repo(
         tempdir_factory, store, 'stdout_stderr_repo',
diff --git a/tests/xargs_test.py b/tests/xargs_test.py
index 0530e50d..7c41f98c 100644
--- a/tests/xargs_test.py
+++ b/tests/xargs_test.py
@@ -187,7 +187,7 @@ def test_xargs_propagate_kwargs_to_cmd():
     assert b'Pre commit is awesome' in stdout
 
 
-@pytest.mark.xfail(os.name == 'nt', reason='posix only')
+@pytest.mark.xfail(sys.platform == 'win32', reason='posix only')
 def test_xargs_color_true_makes_tty():
     retcode, out = xargs.xargs(
         (sys.executable, '-c', 'import sys; print(sys.stdout.isatty())'),