diff --git a/build.rs b/build.rs
deleted file mode 100644
index 8292525..0000000
--- a/build.rs
+++ /dev/null
@@ -1,16 +0,0 @@
-fn main() {
-    let cfg = match autocfg::AutoCfg::new() {
-        Ok(cfg) => cfg,
-        Err(e) => {
-            println!(
-                "cargo:warning=async-io: failed to detect compiler features: {}",
-                e
-            );
-            return;
-        }
-    };
-
-    if !cfg.probe_rustc_version(1, 63) {
-        autocfg::emit("async_io_no_io_safety");
-    }
-}
diff --git a/src/lib.rs b/src/lib.rs
index fd4ab9c..8ebdd94 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -64,8 +64,6 @@ use std::sync::Arc;
 use std::task::{Context, Poll, Waker};
 use std::time::{Duration, Instant};
 
-#[cfg(all(not(async_io_no_io_safety), unix))]
-use std::os::unix::io::{AsFd, BorrowedFd, OwnedFd};
 #[cfg(unix)]
 use std::{
     os::unix::io::{AsRawFd, RawFd},
@@ -75,12 +73,14 @@ use std::{
 
 #[cfg(windows)]
 use std::os::windows::io::{AsRawSocket, RawSocket};
-#[cfg(all(not(async_io_no_io_safety), windows))]
-use std::os::windows::io::{AsSocket, BorrowedSocket, OwnedSocket};
 
 use futures_io::{AsyncRead, AsyncWrite};
 use futures_lite::stream::{self, Stream};
 use futures_lite::{future, pin, ready};
+#[cfg(unix)]
+use rustix::fd::{AsFd, BorrowedFd, OwnedFd};
+#[cfg(windows)]
+use rustix::fd::{AsSocket, BorrowedFd as BorrowedSocket, OwnedFd as OwnedSocket};
 use socket2::{Domain, Protocol, SockAddr, Socket, Type};
 
 use crate::reactor::{Reactor, Source};
@@ -691,14 +691,14 @@ impl<T: AsRawFd> AsRawFd for Async<T> {
     }
 }
 
-#[cfg(all(not(async_io_no_io_safety), unix))]
+#[cfg(unix)]
 impl<T: AsFd> AsFd for Async<T> {
     fn as_fd(&self) -> BorrowedFd<'_> {
         self.get_ref().as_fd()
     }
 }
 
-#[cfg(all(not(async_io_no_io_safety), unix))]
+#[cfg(unix)]
 impl<T: AsRawFd + From<OwnedFd>> TryFrom<OwnedFd> for Async<T> {
     type Error = io::Error;
 
@@ -707,7 +707,7 @@ impl<T: AsRawFd + From<OwnedFd>> TryFrom<OwnedFd> for Async<T> {
     }
 }
 
-#[cfg(all(not(async_io_no_io_safety), unix))]
+#[cfg(unix)]
 impl<T: Into<OwnedFd>> TryFrom<Async<T>> for OwnedFd {
     type Error = io::Error;
 
@@ -767,14 +767,14 @@ impl<T: AsRawSocket> AsRawSocket for Async<T> {
     }
 }
 
-#[cfg(all(not(async_io_no_io_safety), windows))]
+#[cfg(windows)]
 impl<T: AsSocket> AsSocket for Async<T> {
     fn as_socket(&self) -> BorrowedSocket<'_> {
         self.get_ref().as_socket()
     }
 }
 
-#[cfg(all(not(async_io_no_io_safety), windows))]
+#[cfg(windows)]
 impl<T: AsRawSocket + From<OwnedSocket>> TryFrom<OwnedSocket> for Async<T> {
     type Error = io::Error;
 
@@ -783,7 +783,7 @@ impl<T: AsRawSocket + From<OwnedSocket>> TryFrom<OwnedSocket> for Async<T> {
     }
 }
 
-#[cfg(all(not(async_io_no_io_safety), windows))]
+#[cfg(windows)]
 impl<T: Into<OwnedSocket>> TryFrom<Async<T>> for OwnedSocket {
     type Error = io::Error;