diff --git a/crates/wasi-common/yanix/src/dir.rs b/crates/wasi-common/yanix/src/dir.rs
index 12b05686a6..50166a35b1 100644
--- a/crates/wasi-common/yanix/src/dir.rs
+++ b/crates/wasi-common/yanix/src/dir.rs
@@ -4,7 +4,10 @@ use crate::{
 };
 use std::convert::TryInto;
 use std::io::{Error, Result};
+#[cfg(unix)]
 use std::os::unix::io::{AsRawFd, IntoRawFd, RawFd};
+#[cfg(target_os = "wasi")]
+use std::os::wasi::io::{AsRawFd, IntoRawFd, RawFd};
 use std::{ffi::CStr, io, ops::Deref, ptr};
 
 pub use crate::sys::EntryExt;
diff --git a/crates/wasi-common/yanix/src/fcntl.rs b/crates/wasi-common/yanix/src/fcntl.rs
index 12c57cbd47..824b997b9b 100644
--- a/crates/wasi-common/yanix/src/fcntl.rs
+++ b/crates/wasi-common/yanix/src/fcntl.rs
@@ -3,7 +3,10 @@ use crate::{
     from_result, from_success_code,
 };
 use std::io::Result;
+#[cfg(unix)]
 use std::os::unix::prelude::*;
+#[cfg(target_os = "wasi")]
+use std::os::wasi::prelude::*;
 
 pub unsafe fn dup_fd(fd: RawFd, close_on_exec: bool) -> Result<RawFd> {
     // Both fcntl commands expect a RawFd arg which will specify
diff --git a/crates/wasi-common/yanix/src/file.rs b/crates/wasi-common/yanix/src/file.rs
index c525ac444f..10f4aa6a05 100644
--- a/crates/wasi-common/yanix/src/file.rs
+++ b/crates/wasi-common/yanix/src/file.rs
@@ -1,11 +1,14 @@
 use crate::{from_result, from_success_code};
 use bitflags::bitflags;
 use cfg_if::cfg_if;
+#[cfg(unix)]
+use std::os::unix::prelude::*;
+#[cfg(target_os = "wasi")]
+use std::os::wasi::prelude::*;
 use std::{
     convert::TryInto,
     ffi::{CString, OsStr, OsString},
     io::Result,
-    os::unix::prelude::*,
 };
 
 pub use crate::sys::file::*;
@@ -62,6 +65,7 @@ bitflags! {
                              target_os = "macos",
                              target_os = "netbsd",
                              target_os = "openbsd",
+                             target_os = "wasi",
                              target_os = "emscripten"))] {
                     libc::O_DSYNC
                 } else if #[cfg(target_os = "freebsd")] {
@@ -87,6 +91,7 @@ bitflags! {
         #[cfg(any(target_os = "linux",
                   target_os = "netbsd",
                   target_os = "openbsd",
+                  target_os = "wasi",
                   target_os = "emscripten"))]
         const RSYNC = libc::O_RSYNC;
         const SYNC = libc::O_SYNC;
@@ -189,11 +194,11 @@ pub unsafe fn mkdirat<P: AsRef<OsStr>>(dirfd: RawFd, path: P, mode: Mode) -> Res
     from_success_code(libc::mkdirat(dirfd, path.as_ptr(), mode.bits()))
 }
 
-pub unsafe fn linkat<P: AsRef<OsStr>>(
+pub unsafe fn linkat<P: AsRef<OsStr>, Q: AsRef<OsStr>>(
     old_dirfd: RawFd,
     old_path: P,
     new_dirfd: RawFd,
-    new_path: P,
+    new_path: Q,
     flags: AtFlags,
 ) -> Result<()> {
     let old_path = CString::new(old_path.as_ref().as_bytes())?;
@@ -212,11 +217,11 @@ pub unsafe fn unlinkat<P: AsRef<OsStr>>(dirfd: RawFd, path: P, flags: AtFlags) -
     from_success_code(libc::unlinkat(dirfd, path.as_ptr(), flags.bits()))
 }
 
-pub unsafe fn renameat<P: AsRef<OsStr>>(
+pub unsafe fn renameat<P: AsRef<OsStr>, Q: AsRef<OsStr>>(
     old_dirfd: RawFd,
     old_path: P,
     new_dirfd: RawFd,
-    new_path: P,
+    new_path: Q,
 ) -> Result<()> {
     let old_path = CString::new(old_path.as_ref().as_bytes())?;
     let new_path = CString::new(new_path.as_ref().as_bytes())?;
@@ -228,7 +233,11 @@ pub unsafe fn renameat<P: AsRef<OsStr>>(
     ))
 }
 
-pub unsafe fn symlinkat<P: AsRef<OsStr>>(old_path: P, new_dirfd: RawFd, new_path: P) -> Result<()> {
+pub unsafe fn symlinkat<P: AsRef<OsStr>, Q: AsRef<OsStr>>(
+    old_path: P,
+    new_dirfd: RawFd,
+    new_path: Q,
+) -> Result<()> {
     let old_path = CString::new(old_path.as_ref().as_bytes())?;
     let new_path = CString::new(new_path.as_ref().as_bytes())?;
     from_success_code(libc::symlinkat(
diff --git a/crates/wasi-common/yanix/src/lib.rs b/crates/wasi-common/yanix/src/lib.rs
index 955a809436..2b742c4e97 100644
--- a/crates/wasi-common/yanix/src/lib.rs
+++ b/crates/wasi-common/yanix/src/lib.rs
@@ -7,14 +7,17 @@
 //!
 //! [nix]: https://github.com/nix-rust/nix
 //! [wasi-common]: https://github.com/bytecodealliance/wasmtime/tree/main/crates/wasi-common
-#![cfg(unix)]
+#![cfg(any(unix, target_os = "wasi"))]
 
+#[cfg(not(target_os = "wasi"))] // not implemented for WASI in yanix yet
 pub mod clock;
 pub mod dir;
 pub mod fcntl;
 pub mod file;
 pub mod filetime;
+#[cfg(not(target_os = "wasi"))] // not implemented for WASI in yanix yet
 pub mod poll;
+#[cfg(not(target_os = "wasi"))] // not supported in WASI yet
 pub mod socket;
 
 mod sys;
diff --git a/crates/wasi-common/yanix/src/sys/mod.rs b/crates/wasi-common/yanix/src/sys/mod.rs
index e6bd0e36dc..c189768532 100644
--- a/crates/wasi-common/yanix/src/sys/mod.rs
+++ b/crates/wasi-common/yanix/src/sys/mod.rs
@@ -18,6 +18,9 @@ cfg_if! {
                         target_os = "dragonfly"))] {
         mod bsd;
         pub(crate) use bsd::*;
+    } else if #[cfg(target_os = "wasi")] {
+        mod wasi;
+        pub(crate) use wasi::*;
     } else {
         compile_error!("yanix doesn't compile for this platform yet");
     }
diff --git a/crates/wasi-common/yanix/src/sys/wasi/fadvise.rs b/crates/wasi-common/yanix/src/sys/wasi/fadvise.rs
new file mode 100644
index 0000000000..4c8d0fc4ad
--- /dev/null
+++ b/crates/wasi-common/yanix/src/sys/wasi/fadvise.rs
@@ -0,0 +1,23 @@
+use crate::from_success_code;
+use std::io::Result;
+use std::os::wasi::prelude::*;
+
+#[derive(Debug, Copy, Clone)]
+#[repr(i32)]
+pub enum PosixFadviseAdvice {
+    Normal = libc::POSIX_FADV_NORMAL,
+    Sequential = libc::POSIX_FADV_SEQUENTIAL,
+    Random = libc::POSIX_FADV_RANDOM,
+    NoReuse = libc::POSIX_FADV_NOREUSE,
+    WillNeed = libc::POSIX_FADV_WILLNEED,
+    DontNeed = libc::POSIX_FADV_DONTNEED,
+}
+
+pub unsafe fn posix_fadvise(
+    fd: RawFd,
+    offset: libc::off_t,
+    len: libc::off_t,
+    advice: PosixFadviseAdvice,
+) -> Result<()> {
+    from_success_code(libc::posix_fadvise(fd, offset, len, advice as libc::c_int))
+}
diff --git a/crates/wasi-common/yanix/src/sys/wasi/file.rs b/crates/wasi-common/yanix/src/sys/wasi/file.rs
new file mode 100644
index 0000000000..4753d72f42
--- /dev/null
+++ b/crates/wasi-common/yanix/src/sys/wasi/file.rs
@@ -0,0 +1,21 @@
+use std::{
+    io::{Error, Result},
+    os::wasi::prelude::*,
+};
+
+pub unsafe fn isatty(fd: RawFd) -> Result<bool> {
+    let res = libc::isatty(fd);
+    if res == 1 {
+        // isatty() returns 1 if fd is an open file descriptor referring to a terminal...
+        Ok(true)
+    } else {
+        // ... otherwise 0 is returned, and errno is set to indicate the error.
+        let errno = Error::last_os_error();
+        let raw_errno = errno.raw_os_error().unwrap();
+        if raw_errno == libc::ENOTTY {
+            Ok(false)
+        } else {
+            Err(errno)
+        }
+    }
+}
diff --git a/crates/wasi-common/yanix/src/sys/wasi/filetime.rs b/crates/wasi-common/yanix/src/sys/wasi/filetime.rs
new file mode 100644
index 0000000000..7cd8a4483c
--- /dev/null
+++ b/crates/wasi-common/yanix/src/sys/wasi/filetime.rs
@@ -0,0 +1,33 @@
+use crate::filetime::FileTime;
+use crate::from_success_code;
+use std::fs::File;
+use std::io;
+
+pub fn utimensat(
+    dirfd: &File,
+    path: &str,
+    atime: FileTime,
+    mtime: FileTime,
+    symlink_nofollow: bool,
+) -> io::Result<()> {
+    use crate::filetime::to_timespec;
+    use std::ffi::CString;
+    use std::os::wasi::prelude::*;
+
+    let p = CString::new(path.as_bytes())?;
+    let times = [to_timespec(&atime)?, to_timespec(&mtime)?];
+    let flags = if symlink_nofollow {
+        libc::AT_SYMLINK_NOFOLLOW
+    } else {
+        0
+    };
+
+    from_success_code(unsafe {
+        libc::utimensat(
+            dirfd.as_raw_fd() as libc::c_int,
+            p.as_ptr(),
+            times.as_ptr(),
+            flags,
+        )
+    })
+}
diff --git a/crates/wasi-common/yanix/src/sys/wasi/mod.rs b/crates/wasi-common/yanix/src/sys/wasi/mod.rs
new file mode 100644
index 0000000000..104da5e592
--- /dev/null
+++ b/crates/wasi-common/yanix/src/sys/wasi/mod.rs
@@ -0,0 +1,3 @@
+pub(crate) mod fadvise;
+pub(crate) mod file;
+pub(crate) mod filetime;