diff --git a/tests/ptvsd/server/test_path_mapping.py b/tests/ptvsd/server/test_path_mapping.py
index b6fd4873..970fb0af 100644
--- a/tests/ptvsd/server/test_path_mapping.py
+++ b/tests/ptvsd/server/test_path_mapping.py
@@ -15,7 +15,7 @@ from tests.patterns import some
 @pytest.mark.skipif(sys.platform == "win32", reason="Linux/Mac only test.")
 @pytest.mark.parametrize("os_type", ["INVALID", ""])
 def test_client_ide_from_path_mapping_linux_backend(
-    pyfile, tmpdir, start_method, run_as, os_type
+    pyfile, start_method, run_as, os_type
 ):
     """
     Test simulating that the backend is on Linux and the client is on Windows
@@ -65,7 +65,7 @@ def test_client_ide_from_path_mapping_linux_backend(
         session.wait_for_exit()
 
 
-def test_with_dot_remote_root(pyfile, tmpdir, start_method, run_as):
+def test_with_dot_remote_root(pyfile, long_tmpdir, start_method, run_as):
     @pyfile
     def code_to_debug():
         from debug_me import backchannel
@@ -74,8 +74,8 @@ def test_with_dot_remote_root(pyfile, tmpdir, start_method, run_as):
         backchannel.send(os.path.abspath(__file__))
         print("done")  # @bp
 
-    path_local = tmpdir.mkdir("local") / "code_to_debug.py"
-    path_remote = tmpdir.mkdir("remote") / "code_to_debug.py"
+    path_local = long_tmpdir.mkdir("local") / "code_to_debug.py"
+    path_remote = long_tmpdir.mkdir("remote") / "code_to_debug.py"
 
     dir_local = path_local.dirname
     dir_remote = path_remote.dirname
@@ -110,7 +110,7 @@ def test_with_dot_remote_root(pyfile, tmpdir, start_method, run_as):
         session.wait_for_exit()
 
 
-def test_with_path_mappings(pyfile, tmpdir, start_method, run_as):
+def test_with_path_mappings(pyfile, long_tmpdir, start_method, run_as):
     @pyfile
     def code_to_debug():
         from debug_me import backchannel
@@ -129,8 +129,8 @@ def test_with_path_mappings(pyfile, tmpdir, start_method, run_as):
         call_me_back.call_me_back(call_func)  # @call_me_back
         print("done")
 
-    dir_local = tmpdir.mkdir("local")
-    dir_remote = tmpdir.mkdir("remote")
+    dir_local = long_tmpdir.mkdir("local")
+    dir_remote = long_tmpdir.mkdir("remote")
 
     path_local = dir_local / "code_to_debug.py"
     path_remote = dir_remote / "code_to_debug.py"
diff --git a/tests/pytest_fixtures.py b/tests/pytest_fixtures.py
index 9b56ef44..2c02165c 100644
--- a/tests/pytest_fixtures.py
+++ b/tests/pytest_fixtures.py
@@ -7,6 +7,7 @@ from __future__ import absolute_import, print_function, unicode_literals
 import inspect
 import os
 import platform
+import py.path
 import pytest
 import tempfile
 import threading
@@ -97,8 +98,30 @@ def daemon(request):
                 assert not thread.is_alive()
 
 
+if platform.system() != 'Windows':
+    @pytest.fixture
+    def long_tmpdir(request, tmpdir):
+        return tmpdir
+else:
+    import ctypes
+
+    GetLongPathNameW = ctypes.windll.kernel32.GetLongPathNameW
+    GetLongPathNameW.argtypes = [ctypes.c_wchar_p, ctypes.c_wchar_p, ctypes.c_uint32]
+    GetLongPathNameW.restype = ctypes.c_uint32
+
+    @pytest.fixture
+    def long_tmpdir(request, tmpdir):
+        """Like tmpdir, but ensures that it's a long rather than short filename on Win32.
+        """
+        path = compat.filename(tmpdir.strpath)
+        buffer = ctypes.create_unicode_buffer(512)
+        if GetLongPathNameW(path, buffer, len(buffer)):
+            path = buffer.value
+        return py.path.local(path)
+
+
 @pytest.fixture
-def pyfile(request, tmpdir):
+def pyfile(request, long_tmpdir):
     """A fixture providing a factory function that generates .py files.
 
     The returned factory takes a single function with an empty argument list,
@@ -160,7 +183,7 @@ def pyfile(request, tmpdir):
         source = ''.join(source)
 
         # Write it to file.
-        tmpfile = tmpdir / (name + '.py')
+        tmpfile = long_tmpdir / (name + '.py')
         tmpfile.strpath = compat.filename(tmpfile.strpath)
         assert not tmpfile.check()
         tmpfile.write(source)