diff --git a/Cargo.toml b/Cargo.toml
index 1b21e3659..4c8971685 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -269,4 +269,5 @@ check-cfg = [
     'cfg(wasi_ext)',
     'cfg(wasip2)',
     'cfg(target_arch, values("xtensa"))',
+    'cfg(target_os, values("cygwin"))',
 ]
diff --git a/src/backend/libc/fs/types.rs b/src/backend/libc/fs/types.rs
index 865db5465..05c30cba6 100644
--- a/src/backend/libc/fs/types.rs
+++ b/src/backend/libc/fs/types.rs
@@ -381,6 +381,7 @@ bitflags! {
             target_os = "horizon",
             target_os = "wasi",
             target_os = "vita",
+            target_os = "cygwin",
             solarish
         )))]
         const ASYNC = bitcast!(c::O_ASYNC);
@@ -788,6 +789,7 @@ bitflags! {
             target_os = "l4re",
             target_os = "linux",
             target_os = "wasi",
+            target_os = "cygwin",
         )))]
         const NO_HIDE_STALE = bitcast!(c::FALLOC_FL_NO_HIDE_STALE);
         /// `FALLOC_FL_COLLAPSE_RANGE`
@@ -1063,7 +1065,8 @@ pub type StatFs = c::statfs64;
     target_os = "nto",
     target_os = "redox",
     target_os = "vita",
-    target_os = "wasi"
+    target_os = "wasi",
+    target_os = "cygwin"
 )))]
 pub type Fsid = c::fsid_t;
 
diff --git a/src/backend/libc/io/errno.rs b/src/backend/libc/io/errno.rs
index 0312eaf44..e065f9db6 100644
--- a/src/backend/libc/io/errno.rs
+++ b/src/backend/libc/io/errno.rs
@@ -285,6 +285,7 @@ impl Errno {
         target_os = "redox",
         target_os = "vita",
         target_os = "wasi",
+        target_os = "cygwin",
     )))]
     pub const HWPOISON: Self = Self(c::EHWPOISON);
     /// `EIDRM`
@@ -334,6 +335,7 @@ impl Errno {
         target_os = "nto",
         target_os = "vita",
         target_os = "wasi",
+        target_os = "cygwin",
     )))]
     pub const ISNAM: Self = Self(c::EISNAM);
     /// `EKEYEXPIRED`
@@ -350,6 +352,7 @@ impl Errno {
         target_os = "nto",
         target_os = "vita",
         target_os = "wasi",
+        target_os = "cygwin",
     )))]
     pub const KEYEXPIRED: Self = Self(c::EKEYEXPIRED);
     /// `EKEYREJECTED`
@@ -366,6 +369,7 @@ impl Errno {
         target_os = "nto",
         target_os = "vita",
         target_os = "wasi",
+        target_os = "cygwin",
     )))]
     pub const KEYREJECTED: Self = Self(c::EKEYREJECTED);
     /// `EKEYREVOKED`
@@ -382,6 +386,7 @@ impl Errno {
         target_os = "nto",
         target_os = "vita",
         target_os = "wasi",
+        target_os = "cygwin",
     )))]
     pub const KEYREVOKED: Self = Self(c::EKEYREVOKED);
     /// `EL2HLT`
@@ -534,6 +539,7 @@ impl Errno {
         target_os = "nto",
         target_os = "vita",
         target_os = "wasi",
+        target_os = "cygwin",
     )))]
     pub const MEDIUMTYPE: Self = Self(c::EMEDIUMTYPE);
     /// `EMFILE`
@@ -563,6 +569,7 @@ impl Errno {
         target_os = "nto",
         target_os = "vita",
         target_os = "wasi",
+        target_os = "cygwin",
     )))]
     pub const NAVAIL: Self = Self(c::ENAVAIL);
     /// `ENEEDAUTH`
@@ -643,6 +650,7 @@ impl Errno {
         target_os = "nto",
         target_os = "vita",
         target_os = "wasi",
+        target_os = "cygwin",
     )))]
     pub const NOKEY: Self = Self(c::ENOKEY);
     /// `ENOLCK`
@@ -767,6 +775,7 @@ impl Errno {
         target_os = "nto",
         target_os = "vita",
         target_os = "wasi",
+        target_os = "cygwin",
     )))]
     pub const NOTNAM: Self = Self(c::ENOTNAM);
     /// `ENOTRECOVERABLE`
@@ -895,6 +904,7 @@ impl Errno {
         target_os = "nto",
         target_os = "vita",
         target_os = "wasi",
+        target_os = "cygwin",
     )))]
     pub const REMOTEIO: Self = Self(c::EREMOTEIO);
     /// `ERESTART`
@@ -907,7 +917,8 @@ impl Errno {
         target_os = "hurd",
         target_os = "l4re",
         target_os = "vita",
-        target_os = "wasi"
+        target_os = "wasi",
+        target_os = "cygwin",
     )))]
     pub const RESTART: Self = Self(c::ERESTART);
     /// `ERFKILL`
@@ -926,6 +937,7 @@ impl Errno {
         target_os = "redox",
         target_os = "vita",
         target_os = "wasi",
+        target_os = "cygwin",
     )))]
     pub const RFKILL: Self = Self(c::ERFKILL);
     /// `EROFS`
@@ -1024,6 +1036,7 @@ impl Errno {
         target_os = "nto",
         target_os = "vita",
         target_os = "wasi",
+        target_os = "cygwin",
     )))]
     pub const UCLEAN: Self = Self(c::EUCLEAN);
     /// `EUNATCH`
diff --git a/src/backend/libc/io/syscalls.rs b/src/backend/libc/io/syscalls.rs
index 7ade984dd..1a794ebd0 100644
--- a/src/backend/libc/io/syscalls.rs
+++ b/src/backend/libc/io/syscalls.rs
@@ -101,7 +101,8 @@ pub(crate) fn writev(fd: BorrowedFd<'_>, bufs: &[IoSlice<'_>]) -> io::Result<usi
     target_os = "nto",
     target_os = "redox",
     target_os = "solaris",
-    target_os = "vita"
+    target_os = "vita",
+    target_os = "cygwin",
 )))]
 pub(crate) fn preadv(
     fd: BorrowedFd<'_>,
@@ -127,7 +128,8 @@ pub(crate) fn preadv(
     target_os = "horizon",
     target_os = "redox",
     target_os = "solaris",
-    target_os = "vita"
+    target_os = "vita",
+    target_os = "cygwin",
 )))]
 pub(crate) fn pwritev(fd: BorrowedFd<'_>, bufs: &[IoSlice<'_>], offset: u64) -> io::Result<usize> {
     // Silently cast; we'll get `EINVAL` if the value is negative.
diff --git a/src/backend/libc/mm/types.rs b/src/backend/libc/mm/types.rs
index c25b8d094..850dff8aa 100644
--- a/src/backend/libc/mm/types.rs
+++ b/src/backend/libc/mm/types.rs
@@ -88,6 +88,7 @@ bitflags! {
             target_os = "hurd",
             target_os = "nto",
             target_os = "redox",
+            target_os = "cygwin",
         )))]
         const SHARED_VALIDATE = bitcast!(c::MAP_SHARED_VALIDATE);
         /// `MAP_PRIVATE`
@@ -101,6 +102,7 @@ bitflags! {
             target_os = "hurd",
             target_os = "nto",
             target_os = "redox",
+            target_os = "cygwin",
         )))]
         const DENYWRITE = bitcast!(c::MAP_DENYWRITE);
         /// `MAP_FIXED`
@@ -117,6 +119,7 @@ bitflags! {
             target_os = "hurd",
             target_os = "nto",
             target_os = "redox",
+            target_os = "cygwin",
         )))]
         const FIXED_NOREPLACE = bitcast!(c::MAP_FIXED_NOREPLACE);
         /// `MAP_GROWSDOWN`
@@ -128,6 +131,7 @@ bitflags! {
             target_os = "hurd",
             target_os = "nto",
             target_os = "redox",
+            target_os = "cygwin",
         )))]
         const GROWSDOWN = bitcast!(c::MAP_GROWSDOWN);
         /// `MAP_HUGETLB`
@@ -139,6 +143,7 @@ bitflags! {
             target_os = "hurd",
             target_os = "nto",
             target_os = "redox",
+            target_os = "cygwin",
         )))]
         const HUGETLB = bitcast!(c::MAP_HUGETLB);
         /// `MAP_HUGE_2MB`
@@ -153,6 +158,7 @@ bitflags! {
             target_os = "hurd",
             target_os = "nto",
             target_os = "redox",
+            target_os = "cygwin",
         )))]
         const HUGE_2MB = bitcast!(c::MAP_HUGE_2MB);
         /// `MAP_HUGE_1GB`
@@ -167,6 +173,7 @@ bitflags! {
             target_os = "hurd",
             target_os = "nto",
             target_os = "redox",
+            target_os = "cygwin",
         )))]
         const HUGE_1GB = bitcast!(c::MAP_HUGE_1GB);
         /// `MAP_LOCKED`
@@ -178,6 +185,7 @@ bitflags! {
             target_os = "hurd",
             target_os = "nto",
             target_os = "redox",
+            target_os = "cygwin",
         )))]
         const LOCKED = bitcast!(c::MAP_LOCKED);
         /// `MAP_NOCORE`
@@ -204,6 +212,7 @@ bitflags! {
             target_os = "hurd",
             target_os = "nto",
             target_os = "redox",
+            target_os = "cygwin",
         )))]
         const POPULATE = bitcast!(c::MAP_POPULATE);
         /// `MAP_STACK`
@@ -214,6 +223,7 @@ bitflags! {
             target_os = "haiku",
             target_os = "hurd",
             target_os = "redox",
+            target_os = "cygwin",
         )))]
         const STACK = bitcast!(c::MAP_STACK);
         /// `MAP_PREFAULT_READ`
@@ -234,7 +244,8 @@ bitflags! {
             all(
                 linux_kernel,
                 any(target_arch = "mips", target_arch = "mips32r6", target_arch = "mips64", target_arch = "mips64r6"),
-            )
+            ),
+            target_os = "cygwin",
         )))]
         const SYNC = bitcast!(c::MAP_SYNC);
         /// `MAP_UNINITIALIZED`
diff --git a/src/backend/libc/net/msghdr.rs b/src/backend/libc/net/msghdr.rs
index 174cc16ba..a004f82b6 100644
--- a/src/backend/libc/net/msghdr.rs
+++ b/src/backend/libc/net/msghdr.rs
@@ -62,6 +62,7 @@ fn msg_iov_len(len: usize) -> c::c_int {
     target_os = "haiku",
     target_os = "hurd",
     target_os = "nto",
+    target_os = "cygwin",
 ))]
 #[inline]
 fn msg_control_len(len: usize) -> c::socklen_t {
@@ -84,6 +85,7 @@ fn msg_control_len(len: usize) -> c::socklen_t {
     target_os = "redox",
     target_os = "vita",
     target_os = "wasi",
+    target_os = "cygwin",
 )))]
 #[inline]
 fn msg_control_len(len: usize) -> c::size_t {
diff --git a/src/backend/libc/net/send_recv.rs b/src/backend/libc/net/send_recv.rs
index 921c858be..809c19d96 100644
--- a/src/backend/libc/net/send_recv.rs
+++ b/src/backend/libc/net/send_recv.rs
@@ -23,6 +23,7 @@ bitflags! {
             target_os = "hurd",
             target_os = "redox",
             target_os = "vita",
+            target_os = "cygwin",
         )))]
         const CONFIRM = bitcast!(c::MSG_CONFIRM);
         /// `MSG_DONTROUTE`
@@ -44,6 +45,7 @@ bitflags! {
             target_os = "nto",
             target_os = "redox",
             target_os = "vita",
+            target_os = "cygwin",
         )))]
         const MORE = bitcast!(c::MSG_MORE);
         #[cfg(not(any(apple, windows, target_os = "redox", target_os = "vita")))]
@@ -96,6 +98,7 @@ bitflags! {
             target_os = "nto",
             target_os = "redox",
             target_os = "vita",
+            target_os = "cygwin",
         )))]
         const ERRQUEUE = bitcast!(c::MSG_ERRQUEUE);
         /// `MSG_OOB`
diff --git a/src/backend/libc/net/sockopt.rs b/src/backend/libc/net/sockopt.rs
index 1251c7f70..57af6e690 100644
--- a/src/backend/libc/net/sockopt.rs
+++ b/src/backend/libc/net/sockopt.rs
@@ -27,6 +27,7 @@ use crate::net::xdp::{XdpMmapOffsets, XdpOptionsFlags, XdpRingOffset, XdpStatist
     target_os = "netbsd",
     target_os = "nto",
     target_os = "vita",
+    target_os = "cygwin",
 )))]
 use crate::net::AddressFamily;
 #[cfg(any(
@@ -388,6 +389,7 @@ pub(crate) fn socket_send_buffer_size(fd: BorrowedFd<'_>) -> io::Result<usize> {
     target_os = "netbsd",
     target_os = "nto",
     target_os = "vita",
+    target_os = "cygwin",
 )))]
 pub(crate) fn socket_domain(fd: BorrowedFd<'_>) -> io::Result<AddressFamily> {
     let domain: c::c_int = getsockopt(fd, c::SOL_SOCKET, c::SO_DOMAIN)?;
@@ -412,13 +414,13 @@ pub(crate) fn socket_oobinline(fd: BorrowedFd<'_>) -> io::Result<bool> {
     getsockopt(fd, c::SOL_SOCKET, c::SO_OOBINLINE).map(to_bool)
 }
 
-#[cfg(not(any(solarish, windows)))]
+#[cfg(not(any(solarish, windows, target_os = "cygwin")))]
 #[inline]
 pub(crate) fn set_socket_reuseport(fd: BorrowedFd<'_>, value: bool) -> io::Result<()> {
     setsockopt(fd, c::SOL_SOCKET, c::SO_REUSEPORT, from_bool(value))
 }
 
-#[cfg(not(any(solarish, windows)))]
+#[cfg(not(any(solarish, windows, target_os = "cygwin")))]
 #[inline]
 pub(crate) fn socket_reuseport(fd: BorrowedFd<'_>) -> io::Result<bool> {
     getsockopt(fd, c::SOL_SOCKET, c::SO_REUSEPORT).map(to_bool)
diff --git a/src/backend/libc/process/syscalls.rs b/src/backend/libc/process/syscalls.rs
index d288f7016..7338cd75f 100644
--- a/src/backend/libc/process/syscalls.rs
+++ b/src/backend/libc/process/syscalls.rs
@@ -69,7 +69,8 @@ use crate::process::{Resource, Rlimit};
     target_os = "openbsd",
     target_os = "redox",
     target_os = "vita",
-    target_os = "wasi"
+    target_os = "wasi",
+    target_os = "cygwin"
 )))]
 use crate::process::{WaitId, WaitIdOptions, WaitIdStatus};
 use core::mem::MaybeUninit;
@@ -389,7 +390,8 @@ pub(crate) fn _waitpid(
     target_os = "openbsd",
     target_os = "redox",
     target_os = "vita",
-    target_os = "wasi"
+    target_os = "wasi",
+    target_os = "cygwin"
 )))]
 #[inline]
 pub(crate) fn waitid(id: WaitId<'_>, options: WaitIdOptions) -> io::Result<Option<WaitIdStatus>> {
@@ -411,7 +413,8 @@ pub(crate) fn waitid(id: WaitId<'_>, options: WaitIdOptions) -> io::Result<Optio
     target_os = "openbsd",
     target_os = "redox",
     target_os = "vita",
-    target_os = "wasi"
+    target_os = "wasi",
+    target_os = "cygwin"
 )))]
 #[inline]
 fn _waitid_all(options: WaitIdOptions) -> io::Result<Option<WaitIdStatus>> {
@@ -436,7 +439,8 @@ fn _waitid_all(options: WaitIdOptions) -> io::Result<Option<WaitIdStatus>> {
     target_os = "openbsd",
     target_os = "redox",
     target_os = "vita",
-    target_os = "wasi"
+    target_os = "wasi",
+    target_os = "cygwin"
 )))]
 #[inline]
 fn _waitid_pid(pid: Pid, options: WaitIdOptions) -> io::Result<Option<WaitIdStatus>> {
@@ -461,7 +465,8 @@ fn _waitid_pid(pid: Pid, options: WaitIdOptions) -> io::Result<Option<WaitIdStat
     target_os = "openbsd",
     target_os = "redox",
     target_os = "vita",
-    target_os = "wasi"
+    target_os = "wasi",
+    target_os = "cygwin"
 )))]
 #[inline]
 fn _waitid_pgid(pgid: Option<Pid>, options: WaitIdOptions) -> io::Result<Option<WaitIdStatus>> {
@@ -510,7 +515,8 @@ fn _waitid_pidfd(fd: BorrowedFd<'_>, options: WaitIdOptions) -> io::Result<Optio
     target_os = "openbsd",
     target_os = "redox",
     target_os = "vita",
-    target_os = "wasi"
+    target_os = "wasi",
+    target_os = "cygwin"
 )))]
 #[inline]
 unsafe fn cvt_waitid_status(status: MaybeUninit<c::siginfo_t>) -> Option<WaitIdStatus> {
diff --git a/src/backend/libc/process/types.rs b/src/backend/libc/process/types.rs
index ab006e3d6..18ee5ca4f 100644
--- a/src/backend/libc/process/types.rs
+++ b/src/backend/libc/process/types.rs
@@ -39,15 +39,21 @@ pub enum Resource {
     Core = bitcast!(c::RLIMIT_CORE),
     /// `RLIMIT_RSS`
     // "nto" has `RLIMIT_RSS`, but it has the same value as `RLIMIT_AS`.
-    #[cfg(not(any(apple, solarish, target_os = "haiku", target_os = "nto")))]
+    #[cfg(not(any(
+        apple,
+        solarish,
+        target_os = "haiku",
+        target_os = "nto",
+        target_os = "cygwin",
+    )))]
     Rss = bitcast!(c::RLIMIT_RSS),
     /// `RLIMIT_NPROC`
-    #[cfg(not(any(solarish, target_os = "haiku")))]
+    #[cfg(not(any(solarish, target_os = "haiku", target_os = "cygwin")))]
     Nproc = bitcast!(c::RLIMIT_NPROC),
     /// `RLIMIT_NOFILE`
     Nofile = bitcast!(c::RLIMIT_NOFILE),
     /// `RLIMIT_MEMLOCK`
-    #[cfg(not(any(solarish, target_os = "aix", target_os = "haiku")))]
+    #[cfg(not(any(solarish, target_os = "aix", target_os = "haiku", target_os = "cygwin")))]
     Memlock = bitcast!(c::RLIMIT_MEMLOCK),
     /// `RLIMIT_AS`
     #[cfg(not(target_os = "openbsd"))]
@@ -59,7 +65,8 @@ pub enum Resource {
         target_os = "aix",
         target_os = "haiku",
         target_os = "hurd",
-        target_os = "nto"
+        target_os = "nto",
+        target_os = "cygwin"
     )))]
     Locks = bitcast!(c::RLIMIT_LOCKS),
     /// `RLIMIT_SIGPENDING`
@@ -69,7 +76,8 @@ pub enum Resource {
         target_os = "aix",
         target_os = "haiku",
         target_os = "hurd",
-        target_os = "nto"
+        target_os = "nto",
+        target_os = "cygwin"
     )))]
     Sigpending = bitcast!(c::RLIMIT_SIGPENDING),
     /// `RLIMIT_MSGQUEUE`
@@ -79,7 +87,8 @@ pub enum Resource {
         target_os = "aix",
         target_os = "haiku",
         target_os = "hurd",
-        target_os = "nto"
+        target_os = "nto",
+        target_os = "cygwin"
     )))]
     Msgqueue = bitcast!(c::RLIMIT_MSGQUEUE),
     /// `RLIMIT_NICE`
@@ -89,7 +98,8 @@ pub enum Resource {
         target_os = "aix",
         target_os = "haiku",
         target_os = "hurd",
-        target_os = "nto"
+        target_os = "nto",
+        target_os = "cygwin"
     )))]
     Nice = bitcast!(c::RLIMIT_NICE),
     /// `RLIMIT_RTPRIO`
@@ -99,7 +109,8 @@ pub enum Resource {
         target_os = "aix",
         target_os = "haiku",
         target_os = "hurd",
-        target_os = "nto"
+        target_os = "nto",
+        target_os = "cygwin"
     )))]
     Rtprio = bitcast!(c::RLIMIT_RTPRIO),
     /// `RLIMIT_RTTIME`
@@ -112,6 +123,7 @@ pub enum Resource {
         target_os = "haiku",
         target_os = "hurd",
         target_os = "nto",
+        target_os = "cygwin",
     )))]
     Rttime = bitcast!(c::RLIMIT_RTTIME),
 }
diff --git a/src/backend/libc/process/wait.rs b/src/backend/libc/process/wait.rs
index 54c4d404b..5b3e10097 100644
--- a/src/backend/libc/process/wait.rs
+++ b/src/backend/libc/process/wait.rs
@@ -11,6 +11,7 @@ pub(crate) use c::{WCONTINUED, WUNTRACED};
     target_os = "horizon",
     target_os = "openbsd",
     target_os = "redox",
-    target_os = "wasi"
+    target_os = "wasi",
+    target_os = "cygwin"
 )))]
 pub(crate) use c::{WEXITED, WNOWAIT, WSTOPPED};
diff --git a/src/backend/libc/system/syscalls.rs b/src/backend/libc/system/syscalls.rs
index a45ed5fc2..2ddfeddbf 100644
--- a/src/backend/libc/system/syscalls.rs
+++ b/src/backend/libc/system/syscalls.rs
@@ -74,7 +74,8 @@ pub(crate) fn sethostname(name: &[u8]) -> io::Result<()> {
     target_os = "redox",
     target_os = "solaris",
     target_os = "vita",
-    target_os = "wasi"
+    target_os = "wasi",
+    target_os = "cygwin"
 )))]
 pub(crate) fn setdomainname(name: &[u8]) -> io::Result<()> {
     unsafe {
diff --git a/src/clockid.rs b/src/clockid.rs
index b63ad0da1..3b63ac501 100644
--- a/src/clockid.rs
+++ b/src/clockid.rs
@@ -11,8 +11,11 @@ use crate::fd::BorrowedFd;
 /// [`clock_gettime`]: crate::time::clock_gettime
 #[cfg(not(any(apple, target_os = "wasi")))]
 #[derive(Debug, Copy, Clone, Eq, PartialEq, Hash)]
-#[cfg_attr(not(any(target_os = "aix", target_os = "dragonfly")), repr(i32))]
-#[cfg_attr(target_os = "dragonfly", repr(u64))]
+#[cfg_attr(
+    not(any(target_os = "aix", target_os = "dragonfly", target_os = "cygwin")),
+    repr(i32)
+)]
+#[cfg_attr(any(target_os = "dragonfly", target_os = "cygwin"), repr(u64))]
 #[cfg_attr(target_os = "aix", repr(i64))]
 #[non_exhaustive]
 pub enum ClockId {
diff --git a/src/fs/constants.rs b/src/fs/constants.rs
index d5c3821f4..258d5cc20 100644
--- a/src/fs/constants.rs
+++ b/src/fs/constants.rs
@@ -272,7 +272,8 @@ mod tests {
             target_os = "haiku",
             target_os = "nto",
             target_os = "redox",
-            target_os = "wasi"
+            target_os = "wasi",
+            target_os = "cygwin"
         )))]
         {
             check_renamed_type!(Fsid, fsid_t);
diff --git a/src/io/read_write.rs b/src/io/read_write.rs
index ba5dd2912..7a57460cd 100644
--- a/src/io/read_write.rs
+++ b/src/io/read_write.rs
@@ -220,7 +220,8 @@ pub fn writev<Fd: AsFd>(fd: Fd, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
     target_os = "nto",
     target_os = "redox",
     target_os = "solaris",
-    target_os = "vita"
+    target_os = "vita",
+    target_os = "cygwin"
 )))]
 #[inline]
 pub fn preadv<Fd: AsFd>(fd: Fd, bufs: &mut [IoSliceMut<'_>], offset: u64) -> io::Result<usize> {
@@ -258,7 +259,8 @@ pub fn preadv<Fd: AsFd>(fd: Fd, bufs: &mut [IoSliceMut<'_>], offset: u64) -> io:
     target_os = "nto",
     target_os = "redox",
     target_os = "solaris",
-    target_os = "vita"
+    target_os = "vita",
+    target_os = "cygwin"
 )))]
 #[inline]
 pub fn pwritev<Fd: AsFd>(fd: Fd, bufs: &[IoSlice<'_>], offset: u64) -> io::Result<usize> {
diff --git a/src/ioctl/mod.rs b/src/ioctl/mod.rs
index 0a9d7a86e..e9e37aeb3 100644
--- a/src/ioctl/mod.rs
+++ b/src/ioctl/mod.rs
@@ -331,7 +331,8 @@ type _Opcode = c::c_ulong;
     target_os = "fuchsia",
     target_os = "emscripten",
     target_os = "nto",
-    target_os = "wasi"
+    target_os = "wasi",
+    target_os = "cygwin"
 ))]
 type _Opcode = c::c_int;
 
diff --git a/src/net/sockopt.rs b/src/net/sockopt.rs
index 20ed3e72d..f7ed74dc3 100644
--- a/src/net/sockopt.rs
+++ b/src/net/sockopt.rs
@@ -156,6 +156,7 @@ use crate::net::xdp::{XdpMmapOffsets, XdpOptionsFlags, XdpStatistics, XdpUmemReg
     target_os = "netbsd",
     target_os = "nto",
     target_os = "vita",
+    target_os = "cygwin",
 )))]
 use crate::net::AddressFamily;
 #[cfg(any(
@@ -471,6 +472,7 @@ pub fn socket_send_buffer_size<Fd: AsFd>(fd: Fd) -> io::Result<usize> {
     target_os = "netbsd",
     target_os = "nto",
     target_os = "vita",
+    target_os = "cygwin",
 )))]
 #[inline]
 #[doc(alias = "SO_DOMAIN")]
@@ -517,7 +519,7 @@ pub fn socket_oobinline<Fd: AsFd>(fd: Fd) -> io::Result<bool> {
 /// See the [module-level documentation] for more.
 ///
 /// [module-level documentation]: self#references-for-get_socket_-and-set_socket_-functions
-#[cfg(not(any(solarish, windows)))]
+#[cfg(not(any(solarish, windows, target_os = "cygwin")))]
 #[cfg(not(windows))]
 #[inline]
 #[doc(alias = "SO_REUSEPORT")]
@@ -530,7 +532,7 @@ pub fn set_socket_reuseport<Fd: AsFd>(fd: Fd, value: bool) -> io::Result<()> {
 /// See the [module-level documentation] for more.
 ///
 /// [module-level documentation]: self#references-for-get_socket_-and-set_socket_-functions
-#[cfg(not(any(solarish, windows)))]
+#[cfg(not(any(solarish, windows, target_os = "cygwin")))]
 #[inline]
 #[doc(alias = "SO_REUSEPORT")]
 pub fn socket_reuseport<Fd: AsFd>(fd: Fd) -> io::Result<bool> {
diff --git a/src/net/types.rs b/src/net/types.rs
index 660c40887..faee71bca 100644
--- a/src/net/types.rs
+++ b/src/net/types.rs
@@ -102,6 +102,7 @@ impl AddressFamily {
         target_os = "nto",
         target_os = "redox",
         target_os = "vita",
+        target_os = "cygwin",
     )))]
     pub const NETLINK: Self = Self(c::AF_NETLINK as _);
     /// `AF_UNIX`, aka `AF_LOCAL`
@@ -120,6 +121,7 @@ impl AddressFamily {
         target_os = "nto",
         target_os = "redox",
         target_os = "vita",
+        target_os = "cygwin",
     )))]
     pub const AX25: Self = Self(c::AF_AX25 as _);
     /// `AF_IPX`
@@ -129,6 +131,7 @@ impl AddressFamily {
         target_os = "horizon",
         target_os = "redox",
         target_os = "vita",
+        target_os = "cygwin",
     )))]
     pub const IPX: Self = Self(c::AF_IPX as _);
     /// `AF_APPLETALK`
@@ -152,6 +155,7 @@ impl AddressFamily {
         target_os = "nto",
         target_os = "redox",
         target_os = "vita",
+        target_os = "cygwin",
     )))]
     pub const NETROM: Self = Self(c::AF_NETROM as _);
     /// `AF_BRIDGE`
@@ -167,6 +171,7 @@ impl AddressFamily {
         target_os = "nto",
         target_os = "redox",
         target_os = "vita",
+        target_os = "cygwin",
     )))]
     pub const BRIDGE: Self = Self(c::AF_BRIDGE as _);
     /// `AF_ATMPVC`
@@ -182,6 +187,7 @@ impl AddressFamily {
         target_os = "nto",
         target_os = "redox",
         target_os = "vita",
+        target_os = "cygwin",
     )))]
     pub const ATMPVC: Self = Self(c::AF_ATMPVC as _);
     /// `AF_X25`
@@ -196,6 +202,7 @@ impl AddressFamily {
         target_os = "nto",
         target_os = "redox",
         target_os = "vita",
+        target_os = "cygwin",
     )))]
     pub const X25: Self = Self(c::AF_X25 as _);
     /// `AF_ROSE`
@@ -211,6 +218,7 @@ impl AddressFamily {
         target_os = "nto",
         target_os = "redox",
         target_os = "vita",
+        target_os = "cygwin",
     )))]
     pub const ROSE: Self = Self(c::AF_ROSE as _);
     /// `AF_DECnet`
@@ -235,6 +243,7 @@ impl AddressFamily {
         target_os = "nto",
         target_os = "redox",
         target_os = "vita",
+        target_os = "cygwin",
     )))]
     pub const NETBEUI: Self = Self(c::AF_NETBEUI as _);
     /// `AF_SECURITY`
@@ -250,6 +259,7 @@ impl AddressFamily {
         target_os = "nto",
         target_os = "redox",
         target_os = "vita",
+        target_os = "cygwin",
     )))]
     pub const SECURITY: Self = Self(c::AF_SECURITY as _);
     /// `AF_KEY`
@@ -264,6 +274,7 @@ impl AddressFamily {
         target_os = "nto",
         target_os = "redox",
         target_os = "vita",
+        target_os = "cygwin",
     )))]
     pub const KEY: Self = Self(c::AF_KEY as _);
     /// `AF_PACKET`
@@ -283,6 +294,7 @@ impl AddressFamily {
         target_os = "nto",
         target_os = "redox",
         target_os = "vita",
+        target_os = "cygwin",
     )))]
     pub const PACKET: Self = Self(c::AF_PACKET as _);
     /// `AF_ASH`
@@ -298,6 +310,7 @@ impl AddressFamily {
         target_os = "nto",
         target_os = "redox",
         target_os = "vita",
+        target_os = "cygwin",
     )))]
     pub const ASH: Self = Self(c::AF_ASH as _);
     /// `AF_ECONET`
@@ -313,6 +326,7 @@ impl AddressFamily {
         target_os = "nto",
         target_os = "redox",
         target_os = "vita",
+        target_os = "cygwin",
     )))]
     pub const ECONET: Self = Self(c::AF_ECONET as _);
     /// `AF_ATMSVC`
@@ -328,6 +342,7 @@ impl AddressFamily {
         target_os = "nto",
         target_os = "redox",
         target_os = "vita",
+        target_os = "cygwin",
     )))]
     pub const ATMSVC: Self = Self(c::AF_ATMSVC as _);
     /// `AF_RDS`
@@ -343,6 +358,7 @@ impl AddressFamily {
         target_os = "nto",
         target_os = "redox",
         target_os = "vita",
+        target_os = "cygwin",
     )))]
     pub const RDS: Self = Self(c::AF_RDS as _);
     /// `AF_SNA`
@@ -366,6 +382,7 @@ impl AddressFamily {
         target_os = "nto",
         target_os = "redox",
         target_os = "vita",
+        target_os = "cygwin",
     )))]
     pub const IRDA: Self = Self(c::AF_IRDA as _);
     /// `AF_PPPOX`
@@ -381,6 +398,7 @@ impl AddressFamily {
         target_os = "nto",
         target_os = "redox",
         target_os = "vita",
+        target_os = "cygwin",
     )))]
     pub const PPPOX: Self = Self(c::AF_PPPOX as _);
     /// `AF_WANPIPE`
@@ -396,6 +414,7 @@ impl AddressFamily {
         target_os = "nto",
         target_os = "redox",
         target_os = "vita",
+        target_os = "cygwin",
     )))]
     pub const WANPIPE: Self = Self(c::AF_WANPIPE as _);
     /// `AF_LLC`
@@ -411,6 +430,7 @@ impl AddressFamily {
         target_os = "nto",
         target_os = "redox",
         target_os = "vita",
+        target_os = "cygwin",
     )))]
     pub const LLC: Self = Self(c::AF_LLC as _);
     /// `AF_CAN`
@@ -426,6 +446,7 @@ impl AddressFamily {
         target_os = "nto",
         target_os = "redox",
         target_os = "vita",
+        target_os = "cygwin",
     )))]
     pub const CAN: Self = Self(c::AF_CAN as _);
     /// `AF_TIPC`
@@ -441,6 +462,7 @@ impl AddressFamily {
         target_os = "nto",
         target_os = "redox",
         target_os = "vita",
+        target_os = "cygwin",
     )))]
     pub const TIPC: Self = Self(c::AF_TIPC as _);
     /// `AF_BLUETOOTH`
@@ -454,6 +476,7 @@ impl AddressFamily {
         target_os = "hurd",
         target_os = "redox",
         target_os = "vita",
+        target_os = "cygwin",
     )))]
     pub const BLUETOOTH: Self = Self(c::AF_BLUETOOTH as _);
     /// `AF_IUCV`
@@ -469,6 +492,7 @@ impl AddressFamily {
         target_os = "nto",
         target_os = "redox",
         target_os = "vita",
+        target_os = "cygwin",
     )))]
     pub const IUCV: Self = Self(c::AF_IUCV as _);
     /// `AF_RXRPC`
@@ -484,6 +508,7 @@ impl AddressFamily {
         target_os = "nto",
         target_os = "redox",
         target_os = "vita",
+        target_os = "cygwin",
     )))]
     pub const RXRPC: Self = Self(c::AF_RXRPC as _);
     /// `AF_ISDN`
@@ -497,6 +522,7 @@ impl AddressFamily {
         target_os = "hurd",
         target_os = "redox",
         target_os = "vita",
+        target_os = "cygwin",
     )))]
     pub const ISDN: Self = Self(c::AF_ISDN as _);
     /// `AF_PHONET`
@@ -512,6 +538,7 @@ impl AddressFamily {
         target_os = "nto",
         target_os = "redox",
         target_os = "vita",
+        target_os = "cygwin",
     )))]
     pub const PHONET: Self = Self(c::AF_PHONET as _);
     /// `AF_IEEE802154`
@@ -527,6 +554,7 @@ impl AddressFamily {
         target_os = "nto",
         target_os = "redox",
         target_os = "vita",
+        target_os = "cygwin",
     )))]
     pub const IEEE802154: Self = Self(c::AF_IEEE802154 as _);
     /// `AF_802`
@@ -840,7 +868,8 @@ pub mod ipproto {
         target_os = "haiku",
         target_os = "horizon",
         target_os = "redox",
-        target_os = "vita"
+        target_os = "vita",
+        target_os = "cygwin",
     )))]
     pub const TP: Protocol = Protocol(new_raw_protocol(c::IPPROTO_TP as _));
     /// `IPPROTO_DCCP`
@@ -857,6 +886,7 @@ pub mod ipproto {
         target_os = "openbsd",
         target_os = "redox",
         target_os = "vita",
+        target_os = "cygwin",
     )))]
     pub const DCCP: Protocol = Protocol(new_raw_protocol(c::IPPROTO_DCCP as _));
     /// `IPPROTO_IPV6`
@@ -869,7 +899,8 @@ pub mod ipproto {
         target_os = "haiku",
         target_os = "horizon",
         target_os = "redox",
-        target_os = "vita"
+        target_os = "vita",
+        target_os = "cygwin",
     )))]
     pub const RSVP: Protocol = Protocol(new_raw_protocol(c::IPPROTO_RSVP as _));
     /// `IPPROTO_GRE`
@@ -880,7 +911,8 @@ pub mod ipproto {
         target_os = "haiku",
         target_os = "horizon",
         target_os = "redox",
-        target_os = "vita"
+        target_os = "vita",
+        target_os = "cygwin",
     )))]
     pub const GRE: Protocol = Protocol(new_raw_protocol(c::IPPROTO_GRE as _));
     /// `IPPROTO_ESP`
@@ -915,6 +947,7 @@ pub mod ipproto {
         target_os = "nto",
         target_os = "redox",
         target_os = "vita",
+        target_os = "cygwin",
     )))]
     pub const MTP: Protocol = Protocol(new_raw_protocol(c::IPPROTO_MTP as _));
     /// `IPPROTO_BEETPH`
@@ -929,6 +962,7 @@ pub mod ipproto {
         target_os = "nto",
         target_os = "redox",
         target_os = "vita",
+        target_os = "cygwin",
     )))]
     pub const BEETPH: Protocol = Protocol(new_raw_protocol(c::IPPROTO_BEETPH as _));
     /// `IPPROTO_ENCAP`
@@ -941,6 +975,7 @@ pub mod ipproto {
         target_os = "horizon",
         target_os = "redox",
         target_os = "vita",
+        target_os = "cygwin",
     )))]
     pub const ENCAP: Protocol = Protocol(new_raw_protocol(c::IPPROTO_ENCAP as _));
     /// `IPPROTO_PIM`
@@ -951,7 +986,8 @@ pub mod ipproto {
         target_os = "haiku",
         target_os = "horizon",
         target_os = "redox",
-        target_os = "vita"
+        target_os = "vita",
+        target_os = "cygwin",
     )))]
     pub const PIM: Protocol = Protocol(new_raw_protocol(c::IPPROTO_PIM as _));
     /// `IPPROTO_COMP`
@@ -966,6 +1002,7 @@ pub mod ipproto {
         target_os = "nto",
         target_os = "redox",
         target_os = "vita",
+        target_os = "cygwin",
     )))]
     pub const COMP: Protocol = Protocol(new_raw_protocol(c::IPPROTO_COMP as _));
     /// `IPPROTO_SCTP`
@@ -978,6 +1015,7 @@ pub mod ipproto {
         target_os = "openbsd",
         target_os = "redox",
         target_os = "vita",
+        target_os = "cygwin",
     )))]
     pub const SCTP: Protocol = Protocol(new_raw_protocol(c::IPPROTO_SCTP as _));
     /// `IPPROTO_UDPLITE`
@@ -994,6 +1032,7 @@ pub mod ipproto {
         target_os = "nto",
         target_os = "redox",
         target_os = "vita",
+        target_os = "cygwin",
     )))]
     pub const UDPLITE: Protocol = Protocol(new_raw_protocol(c::IPPROTO_UDPLITE as _));
     /// `IPPROTO_MPLS`
@@ -1010,6 +1049,7 @@ pub mod ipproto {
         target_os = "nto",
         target_os = "redox",
         target_os = "vita",
+        target_os = "cygwin",
     )))]
     pub const MPLS: Protocol = Protocol(new_raw_protocol(c::IPPROTO_MPLS as _));
     /// `IPPROTO_ETHERNET`
@@ -1032,6 +1072,7 @@ pub mod ipproto {
         target_os = "nto",
         target_os = "redox",
         target_os = "vita",
+        target_os = "cygwin",
     )))]
     pub const MPTCP: Protocol = Protocol(new_raw_protocol(c::IPPROTO_MPTCP as _));
     /// `IPPROTO_FRAGMENT`
@@ -1059,6 +1100,7 @@ pub mod ipproto {
         target_os = "nto",
         target_os = "redox",
         target_os = "vita",
+        target_os = "cygwin",
     )))]
     pub const MH: Protocol = Protocol(new_raw_protocol(c::IPPROTO_MH as _));
     /// `IPPROTO_ROUTING`
diff --git a/src/process/wait.rs b/src/process/wait.rs
index 5381cd042..4dee1d17c 100644
--- a/src/process/wait.rs
+++ b/src/process/wait.rs
@@ -60,10 +60,13 @@ bitflags! {
         /// [`Signal::Cont`]: crate::process::Signal::Cont
         const CONTINUED = bitcast!(backend::process::wait::WCONTINUED);
         /// Wait for processed that have exited.
+        #[cfg(not(target_os = "cygwin"))]
         const EXITED = bitcast!(backend::process::wait::WEXITED);
         /// Keep processed in a waitable state.
+        #[cfg(not(target_os = "cygwin"))]
         const NOWAIT = bitcast!(backend::process::wait::WNOWAIT);
         /// Wait for processes that have been stopped.
+        #[cfg(not(target_os = "cygwin"))]
         const STOPPED = bitcast!(backend::process::wait::WSTOPPED);
 
         /// <https://docs.rs/bitflags/*/bitflags/#externally-defined-flags>
@@ -485,7 +488,8 @@ pub fn wait(waitopts: WaitOptions) -> io::Result<Option<(Pid, WaitStatus)>> {
     target_os = "horizon",
     target_os = "openbsd",
     target_os = "redox",
-    target_os = "wasi"
+    target_os = "wasi",
+    target_os = "cygwin"
 )))]
 #[inline]
 pub fn waitid<'a, Id: Into<WaitId<'a>>>(
diff --git a/src/signal.rs b/src/signal.rs
index 33026e350..e3eaaa153 100644
--- a/src/signal.rs
+++ b/src/signal.rs
@@ -105,7 +105,8 @@ impl Signal {
                 target_arch = "sparc",
                 target_arch = "sparc64"
             ),
-        )
+        ),
+        target_os = "cygwin",
     )))]
     pub const STKFLT: Self = Self(unsafe { NonZeroI32::new_unchecked(c::SIGSTKFLT) });
     /// `SIGCHLD`
@@ -295,7 +296,8 @@ impl fmt::Debug for Signal {
                         target_arch = "sparc",
                         target_arch = "sparc64"
                     ),
-                )
+                ),
+                target_os = "cygwin",
             )))]
             Self::STKFLT => "Signal::STKFLT".fmt(f),
             #[cfg(not(target_os = "vita"))]
diff --git a/src/system.rs b/src/system.rs
index bfb212f3b..a5a3a7b55 100644
--- a/src/system.rs
+++ b/src/system.rs
@@ -182,7 +182,8 @@ pub fn sethostname(name: &[u8]) -> io::Result<()> {
     target_os = "redox",
     target_os = "solaris",
     target_os = "vita",
-    target_os = "wasi"
+    target_os = "wasi",
+    target_os = "cygwin"
 )))]
 #[inline]
 pub fn setdomainname(name: &[u8]) -> io::Result<()> {
diff --git a/src/termios/mod.rs b/src/termios/mod.rs
index e6b7c9171..ff6f56fb4 100644
--- a/src/termios/mod.rs
+++ b/src/termios/mod.rs
@@ -9,7 +9,12 @@
 //! [`Termios::set_output_speed`], and they will simply fail if the speed is
 //! not supported by the platform or the device.
 
-#[cfg(not(any(target_os = "espidf", target_os = "haiku", target_os = "wasi")))]
+#[cfg(not(any(
+    target_os = "espidf",
+    target_os = "haiku",
+    target_os = "wasi",
+    target_os = "cygwin"
+)))]
 mod ioctl;
 #[cfg(not(target_os = "wasi"))]
 mod tc;
@@ -18,7 +23,12 @@ mod tty;
 #[cfg(not(any(target_os = "espidf", target_os = "wasi")))]
 mod types;
 
-#[cfg(not(any(target_os = "espidf", target_os = "haiku", target_os = "wasi")))]
+#[cfg(not(any(
+    target_os = "espidf",
+    target_os = "haiku",
+    target_os = "wasi",
+    target_os = "cygwin"
+)))]
 pub use ioctl::*;
 #[cfg(not(target_os = "wasi"))]
 pub use tc::*;
diff --git a/src/termios/types.rs b/src/termios/types.rs
index 5b1d68770..88e5068fa 100644
--- a/src/termios/types.rs
+++ b/src/termios/types.rs
@@ -605,7 +605,7 @@ bitflags! {
         const ECHOCTL = c::ECHOCTL;
 
         /// `ECHOPRT`
-        #[cfg(not(any(target_os = "nto", target_os = "redox")))]
+        #[cfg(not(any(target_os = "nto", target_os = "redox", target_os = "cygwin")))]
         const ECHOPRT = c::ECHOPRT;
 
         /// `ECHOKE`
@@ -617,11 +617,17 @@ bitflags! {
         const FLUSHO = c::FLUSHO;
 
         /// `PENDIN`
-        #[cfg(not(any(target_os = "nto", target_os = "redox")))]
+        #[cfg(not(any(target_os = "nto", target_os = "redox", target_os = "cygwin")))]
         const PENDIN = c::PENDIN;
 
         /// `EXTPROC`
-        #[cfg(not(any(target_os = "aix", target_os = "haiku", target_os = "nto", target_os = "redox")))]
+        #[cfg(not(any(
+            target_os = "aix",
+            target_os = "haiku",
+            target_os = "nto",
+            target_os = "redox",
+            target_os = "cygwin",
+        )))]
         const EXTPROC = c::EXTPROC;
 
         /// `ISIG`
@@ -953,6 +959,7 @@ pub mod speed {
                 target_os = "haiku",
                 target_os = "nto",
                 target_os = "solaris",
+                target_os = "cygwin",
             )))]
             c::B3500000 => Some(3_500_000),
             #[cfg(not(any(
@@ -963,6 +970,7 @@ pub mod speed {
                 target_os = "haiku",
                 target_os = "nto",
                 target_os = "solaris",
+                target_os = "cygwin",
             )))]
             c::B4000000 => Some(4_000_000),
             _ => None,
@@ -1090,6 +1098,7 @@ pub mod speed {
                 target_os = "haiku",
                 target_os = "nto",
                 target_os = "solaris",
+                target_os = "cygwin",
             )))]
             3_500_000 => Some(c::B3500000),
             #[cfg(not(any(
@@ -1100,6 +1109,7 @@ pub mod speed {
                 target_os = "haiku",
                 target_os = "nto",
                 target_os = "solaris",
+                target_os = "cygwin",
             )))]
             4_000_000 => Some(c::B4000000),
             _ => None,
diff --git a/tests/fs/chmodat.rs b/tests/fs/chmodat.rs
index 8d990932a..6bc399998 100644
--- a/tests/fs/chmodat.rs
+++ b/tests/fs/chmodat.rs
@@ -1,4 +1,4 @@
-#[cfg(not(target_os = "wasi"))]
+#[cfg(not(any(target_os = "wasi", target_os = "cygwin")))]
 #[test]
 fn test_chmod() {
     use rustix::fs::{chmod, open, stat, symlink, Mode, OFlags};
diff --git a/tests/fs/dir.rs b/tests/fs/dir.rs
index b3a754c9e..195898ecd 100644
--- a/tests/fs/dir.rs
+++ b/tests/fs/dir.rs
@@ -227,7 +227,7 @@ fn dir_iterator_handles_dir_removal() {
 
 // Like `dir_iterator_handles_dir_removal`, but close the directory after
 // `Dir::read_from`.
-#[cfg_attr(any(apple, freebsdlike), ignore)]
+#[cfg_attr(any(apple, freebsdlike, target_os = "cygwin"), ignore)]
 #[test]
 fn dir_iterator_handles_dir_removal_after_open() {
     // create a dir, keep the FD, then delete the dir
diff --git a/tests/fs/file.rs b/tests/fs/file.rs
index 2e4b62309..cd30696bd 100644
--- a/tests/fs/file.rs
+++ b/tests/fs/file.rs
@@ -102,6 +102,7 @@ fn test_file() {
     )))]
     rustix::fs::fadvise(&file, 0, NonZeroU64::new(10), rustix::fs::Advice::Normal).unwrap();
 
+    #[cfg(not(target_os = "cygwin"))]
     rustix::fs::fsync(&file).unwrap();
 
     #[cfg(not(any(
@@ -109,6 +110,7 @@ fn test_file() {
         target_os = "dragonfly",
         target_os = "espidf",
         target_os = "haiku",
+        target_os = "cygwin",
     )))]
     rustix::fs::fdatasync(&file).unwrap();
 
@@ -156,6 +158,7 @@ fn test_file() {
         assert!(statvfs.f_frsize > 0);
     }
 
+    #[cfg(not(target_os = "cygwin"))]
     assert_ne!(rustix::io::ioctl_fionread(&file).unwrap(), 0);
 }
 
diff --git a/tests/fs/invalid_offset.rs b/tests/fs/invalid_offset.rs
index be5f04717..5143622d3 100644
--- a/tests/fs/invalid_offset.rs
+++ b/tests/fs/invalid_offset.rs
@@ -64,6 +64,7 @@ fn invalid_offset_fallocate() {
     target_os = "dragonfly",
     target_os = "haiku",
     target_os = "redox",
+    target_os = "cygwin",
 )))]
 #[test]
 fn invalid_offset_fadvise() {
@@ -158,7 +159,7 @@ fn invalid_offset_pread() {
     pread(&file, &mut buf, i64::MAX as u64 + 1).unwrap_err();
 }
 
-#[cfg(not(apple))]
+#[cfg(not(any(apple, target_os = "cygwin")))]
 #[test]
 fn invalid_offset_pwrite() {
     use rustix::fs::{openat, Mode, OFlags, CWD};
diff --git a/tests/fs/makedev.rs b/tests/fs/makedev.rs
index ba9f9c53d..dfbd8ab07 100644
--- a/tests/fs/makedev.rs
+++ b/tests/fs/makedev.rs
@@ -10,7 +10,9 @@ fn makedev_roundtrip() {
     let (maj, min) = (0x0000_0026, 0x0064_6361);
     #[cfg(target_os = "netbsd")]
     let (maj, min) = (0x0000_0026, 0x0000_0061);
-    #[cfg(not(any(apple, freebsdlike, target_os = "netbsd")))]
+    #[cfg(target_os = "cygwin")]
+    let (maj, min) = (0x0000_2526, 0x0000_6361);
+    #[cfg(not(any(apple, freebsdlike, target_os = "netbsd", target_os = "cygwin")))]
     let (maj, min) = (0x2324_2526, 0x6564_6361);
 
     let dev = makedev(maj, min);
diff --git a/tests/fs/negative_timestamp.rs b/tests/fs/negative_timestamp.rs
index 3f5532c89..b367fbb30 100644
--- a/tests/fs/negative_timestamp.rs
+++ b/tests/fs/negative_timestamp.rs
@@ -1,4 +1,5 @@
 #[cfg(not(target_os = "redox"))]
+#[cfg(not(target_os = "cygwin"))]
 #[test]
 fn negative_file_timestamp() {
     use rustix::fs::{
diff --git a/tests/fs/y2038.rs b/tests/fs/y2038.rs
index 6b49a823c..749dd043f 100644
--- a/tests/fs/y2038.rs
+++ b/tests/fs/y2038.rs
@@ -6,6 +6,7 @@
 #[cfg(not(all(target_os = "android", target_pointer_width = "32")))]
 #[cfg(not(all(target_os = "emscripten", target_pointer_width = "32")))]
 #[cfg(not(target_os = "redox"))]
+#[cfg(not(target_os = "cygwin"))]
 #[test]
 fn test_y2038_with_utimensat() {
     use rustix::fs::{
@@ -81,6 +82,7 @@ fn test_y2038_with_utimensat() {
 #[cfg(not(all(target_os = "android", target_pointer_width = "32")))]
 #[cfg(not(all(target_os = "emscripten", target_pointer_width = "32")))]
 #[cfg(not(target_os = "redox"))]
+#[cfg(not(target_os = "cygwin"))]
 #[test]
 fn test_y2038_with_futimens() {
     use rustix::fs::{
@@ -155,6 +157,7 @@ fn test_y2038_with_futimens() {
 #[cfg(not(all(target_env = "musl", target_pointer_width = "32")))]
 #[cfg(not(all(target_os = "android", target_pointer_width = "32")))]
 #[cfg(not(all(target_os = "emscripten", target_pointer_width = "32")))]
+#[cfg(not(target_os = "cygwin"))]
 #[test]
 fn test_y2038_with_futimens_and_stat() {
     use rustix::fs::{fstat, futimens, open, stat, Mode, OFlags, Timespec, Timestamps};
diff --git a/tests/io/read_write.rs b/tests/io/read_write.rs
index 4ddd89164..6d6daa93a 100644
--- a/tests/io/read_write.rs
+++ b/tests/io/read_write.rs
@@ -5,6 +5,7 @@ use std::io::{IoSlice, IoSliceMut};
 #[cfg(not(target_os = "espidf"))] // no preadv/pwritev
 #[cfg(not(target_os = "solaris"))] // no preadv/pwritev
 #[cfg(not(target_os = "haiku"))] // no preadv/pwritev
+#[cfg(not(target_os = "cygwin"))] // no preadv/pwritev
 #[test]
 fn test_readwrite_pv() {
     use rustix::fs::{openat, Mode, OFlags, CWD};