diff --git a/src/borg/platform/__init__.py b/src/borg/platform/__init__.py
index 1d974f37b..aa980c88d 100644
--- a/src/borg/platform/__init__.py
+++ b/src/borg/platform/__init__.py
@@ -4,7 +4,7 @@ Platform-specific APIs.
 Public APIs are documented in platform.base.
 """
 
-from ..platformflags import is_win32, is_linux, is_freebsd, is_darwin
+from ..platformflags import is_win32, is_linux, is_freebsd, is_darwin, is_cygwin
 
 from .base import listxattr, getxattr, setxattr, ENOATTR
 from .base import acl_get, acl_set
diff --git a/src/borg/platformflags.py b/src/borg/platformflags.py
index 41ec94681..0ab9bf515 100644
--- a/src/borg/platformflags.py
+++ b/src/borg/platformflags.py
@@ -7,6 +7,8 @@ Use these flags instead of sys.platform.startswith('<OS>') or try/except.
 import sys
 
 is_win32 = sys.platform.startswith('win32')
+is_cygwin = sys.platform.startswith('cygwin')
+
 is_linux = sys.platform.startswith('linux')
 is_freebsd = sys.platform.startswith('freebsd')
 is_netbsd = sys.platform.startswith('netbsd')
diff --git a/src/borg/testsuite/helpers.py b/src/borg/testsuite/helpers.py
index e45304039..c22c5b913 100644
--- a/src/borg/testsuite/helpers.py
+++ b/src/borg/testsuite/helpers.py
@@ -31,7 +31,7 @@ from ..helpers import dash_open
 from ..helpers import iter_separated
 from ..helpers import eval_escapes
 from ..helpers import classify_ec, max_ec
-from ..platform import is_win32, swidth
+from ..platform import is_win32, swidth, is_cygwin
 
 from . import BaseTestCase, FakeInputs
 
@@ -582,8 +582,9 @@ def test_get_base_dir(monkeypatch):
     monkeypatch.delenv('HOME', raising=False)
     monkeypatch.delenv('USER', raising=False)
     assert get_base_dir() == os.path.expanduser('~')
-    monkeypatch.setenv('USER', 'root')
-    assert get_base_dir() == os.path.expanduser('~root')
+    if not is_cygwin:
+        monkeypatch.setenv('USER', 'root')
+        assert get_base_dir() == os.path.expanduser('~root')
     monkeypatch.setenv('HOME', '/var/tmp/home')
     assert get_base_dir() == '/var/tmp/home'
     monkeypatch.setenv('BORG_BASE_DIR', '/var/tmp/base')