diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index 22959050..b4f7f62f 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -150,6 +150,7 @@ jobs:
         riscv64gc-unknown-linux-gnu
         arm-unknown-linux-gnueabihf
         aarch64-linux-android
+        wasm32-wasi
     - run: cargo check --workspace --all-targets --all-features --release -vv
     - run: cargo check --workspace --all-targets --all-features --release -vv --target=x86_64-unknown-linux-musl
     - run: cargo check --workspace --all-targets --all-features --release -vv --target=x86_64-unknown-linux-gnux32
@@ -163,6 +164,7 @@ jobs:
     - run: cargo check --workspace --all-targets --all-features --release -vv --target=riscv64gc-unknown-linux-gnu
     - run: cargo check --workspace --all-targets --all-features --release -vv --target=arm-unknown-linux-gnueabihf
     - run: cargo check --workspace --all-targets --all-features --release -vv --target=aarch64-linux-android
+    - run: cd cap-std && cargo check --features=fs_utf8 --release -vv
 
   check_cross_nightly_windows:
     name: Check Cross-Compilation on Rust nightly on Windows
diff --git a/cap-primitives/src/fs/dir_options.rs b/cap-primitives/src/fs/dir_options.rs
index d9c6a7f8..358492eb 100644
--- a/cap-primitives/src/fs/dir_options.rs
+++ b/cap-primitives/src/fs/dir_options.rs
@@ -1,3 +1,4 @@
+#[cfg(not(target_os = "wasi"))]
 use crate::fs::DirOptionsExt;
 
 /// Options and flags which can be used to configure how a directory is
@@ -6,6 +7,7 @@ use crate::fs::DirOptionsExt;
 /// This is to `create_dir` what to `OpenOptions` is to `open`.
 #[derive(Debug, Clone)]
 pub struct DirOptions {
+    #[cfg(not(target_os = "wasi"))]
     #[allow(dead_code)]
     pub(crate) ext: DirOptionsExt,
 }
@@ -16,6 +18,7 @@ impl DirOptions {
     #[inline]
     pub const fn new() -> Self {
         Self {
+            #[cfg(not(target_os = "wasi"))]
             ext: DirOptionsExt::new(),
         }
     }
diff --git a/cap-primitives/src/fs/metadata.rs b/cap-primitives/src/fs/metadata.rs
index 3302a90e..58aad8f3 100644
--- a/cap-primitives/src/fs/metadata.rs
+++ b/cap-primitives/src/fs/metadata.rs
@@ -259,6 +259,44 @@ impl std::os::unix::fs::MetadataExt for Metadata {
     }
 }
 
+#[cfg(target_os = "wasi")]
+impl std::os::wasi::fs::MetadataExt for Metadata {
+    #[inline]
+    fn dev(&self) -> u64 {
+        self.ext.dev()
+    }
+
+    #[inline]
+    fn ino(&self) -> u64 {
+        self.ext.ino()
+    }
+
+    #[inline]
+    fn nlink(&self) -> u64 {
+        self.ext.nlink()
+    }
+
+    #[inline]
+    fn size(&self) -> u64 {
+        self.ext.size()
+    }
+
+    #[inline]
+    fn atim(&self) -> u64 {
+        self.ext.atim()
+    }
+
+    #[inline]
+    fn mtim(&self) -> u64 {
+        self.ext.mtim()
+    }
+
+    #[inline]
+    fn ctim(&self) -> u64 {
+        self.ext.ctim()
+    }
+}
+
 #[cfg(target_os = "vxworks")]
 impl std::os::vxworks::fs::MetadataExt for Metadata {
     #[inline]
diff --git a/cap-primitives/src/fs/mod.rs b/cap-primitives/src/fs/mod.rs
index 9172d855..70853687 100644
--- a/cap-primitives/src/fs/mod.rs
+++ b/cap-primitives/src/fs/mod.rs
@@ -32,6 +32,7 @@ mod remove_file;
 mod remove_open_dir;
 mod rename;
 mod reopen;
+#[cfg(not(target_os = "wasi"))]
 mod set_permissions;
 mod set_times;
 mod stat;
@@ -85,6 +86,7 @@ pub use remove_file::remove_file;
 pub use remove_open_dir::{remove_open_dir, remove_open_dir_all};
 pub use rename::rename;
 pub use reopen::reopen;
+#[cfg(not(target_os = "wasi"))]
 pub use set_permissions::set_permissions;
 pub use set_times::{set_times, set_times_nofollow};
 pub use stat::stat;
diff --git a/cap-primitives/src/fs/open_options.rs b/cap-primitives/src/fs/open_options.rs
index 8b3b55be..de634785 100644
--- a/cap-primitives/src/fs/open_options.rs
+++ b/cap-primitives/src/fs/open_options.rs
@@ -178,6 +178,41 @@ impl std::os::unix::fs::OpenOptionsExt for OpenOptions {
     }
 }
 
+#[cfg(target_os = "wasi")]
+impl std::os::wasi::fs::OpenOptionsExt for OpenOptions {
+    fn lookup_flags(&mut self, _: u32) -> &mut Self {
+        todo!()
+    }
+    fn directory(&mut self, dir_required: bool) -> &mut Self {
+        self.dir_required = dir_required;
+        self
+    }
+    fn dsync(&mut self, _: bool) -> &mut Self {
+        todo!()
+    }
+    fn nonblock(&mut self, _: bool) -> &mut Self {
+        todo!()
+    }
+    fn rsync(&mut self, _: bool) -> &mut Self {
+        todo!()
+    }
+    fn sync(&mut self, _: bool) -> &mut Self {
+        todo!()
+    }
+    fn fs_rights_base(&mut self, _: u64) -> &mut Self {
+        todo!()
+    }
+    fn fs_rights_inheriting(&mut self, _: u64) -> &mut Self {
+        todo!()
+    }
+    fn open_at<P>(&self, dirfd: &std::fs::File, path: P) -> Result<std::fs::File, std::io::Error>
+    where
+        P: AsRef<std::path::Path>,
+    {
+        crate::fs::open(dirfd, path.as_ref(), self)
+    }
+}
+
 #[cfg(target_os = "vxworks")]
 impl std::os::vxworks::fs::OpenOptionsExt for OpenOptions {
     #[inline]
diff --git a/cap-primitives/src/fs/permissions.rs b/cap-primitives/src/fs/permissions.rs
index 9d9f9ac1..be356b68 100644
--- a/cap-primitives/src/fs/permissions.rs
+++ b/cap-primitives/src/fs/permissions.rs
@@ -1,4 +1,4 @@
-#[cfg(any(unix, target_os = "vxworks"))]
+#[cfg(not(windows))]
 use crate::fs::PermissionsExt;
 #[cfg(unix)]
 use rustix::fs::RawMode;
@@ -52,6 +52,15 @@ impl Permissions {
         Ok(fs::Permissions::from_mode(self.ext.mode()))
     }
 
+    #[cfg(target_os = "wasi")]
+    #[inline]
+    #[allow(clippy::unnecessary_wraps)]
+    fn _into_std(self, file: &fs::File) -> io::Result<fs::Permissions> {
+        let mut permissions = file.metadata()?.permissions();
+        permissions.set_readonly(self.readonly());
+        Ok(permissions)
+    }
+
     #[cfg(windows)]
     #[inline]
     fn _into_std(self, file: &fs::File) -> io::Result<fs::Permissions> {
diff --git a/cap-primitives/src/rustix/fs/copy_impl.rs b/cap-primitives/src/rustix/fs/copy_impl.rs
index 312a7928..561a6ac7 100644
--- a/cap-primitives/src/rustix/fs/copy_impl.rs
+++ b/cap-primitives/src/rustix/fs/copy_impl.rs
@@ -25,6 +25,7 @@ fn open_from(start: &fs::File, path: &Path) -> io::Result<(fs::File, fs::Metadat
     Ok((reader, metadata))
 }
 
+#[cfg(not(target_os = "wasi"))]
 fn open_to_and_set_permissions(
     start: &fs::File,
     path: &Path,
@@ -54,6 +55,25 @@ fn open_to_and_set_permissions(
     Ok((writer, writer_metadata))
 }
 
+#[cfg(target_os = "wasi")]
+fn open_to_and_set_permissions(
+    start: &fs::File,
+    path: &Path,
+    reader_metadata: fs::Metadata,
+) -> io::Result<(fs::File, fs::Metadata)> {
+    let writer = open(
+        start,
+        path,
+        OpenOptions::new()
+            // create the file with the correct mode right away
+            .write(true)
+            .create(true)
+            .truncate(true),
+    )?;
+    let writer_metadata = writer.metadata()?;
+    Ok((writer, writer_metadata))
+}
+
 #[cfg(not(any(
     target_os = "linux",
     target_os = "android",
diff --git a/cap-primitives/src/rustix/fs/create_dir_unchecked.rs b/cap-primitives/src/rustix/fs/create_dir_unchecked.rs
index 38dbd11c..652162c7 100644
--- a/cap-primitives/src/rustix/fs/create_dir_unchecked.rs
+++ b/cap-primitives/src/rustix/fs/create_dir_unchecked.rs
@@ -10,9 +10,10 @@ pub(crate) fn create_dir_unchecked(
     path: &Path,
     options: &DirOptions,
 ) -> io::Result<()> {
-    Ok(mkdirat(
-        start,
-        path,
-        Mode::from_bits(options.ext.mode as RawMode).unwrap(),
-    )?)
+    #[cfg(not(target_os = "wasi"))]
+    let raw_mode = options.ext.mode as RawMode;
+    #[cfg(target_os = "wasi")]
+    let raw_mode = 0;
+
+    Ok(mkdirat(start, path, Mode::from_bits(raw_mode).unwrap())?)
 }
diff --git a/cap-primitives/src/rustix/fs/dir_utils.rs b/cap-primitives/src/rustix/fs/dir_utils.rs
index 85e04b47..bb18ee02 100644
--- a/cap-primitives/src/rustix/fs/dir_utils.rs
+++ b/cap-primitives/src/rustix/fs/dir_utils.rs
@@ -6,7 +6,7 @@ use std::ops::Deref;
 #[cfg(unix)]
 use std::os::unix::{ffi::OsStrExt, fs::OpenOptionsExt};
 #[cfg(target_os = "wasi")]
-use std::os::wasi::{ffi::OsStrExt, fs::OpenOptionsExt};
+use std::os::wasi::ffi::OsStrExt;
 use std::path::Path;
 #[cfg(racy_asserts)]
 use std::{ffi::OsString, os::unix::ffi::OsStringExt, path::PathBuf};
@@ -104,10 +104,13 @@ pub(crate) fn open_ambient_dir_impl(path: &Path, _: AmbientAuthority) -> io::Res
     // `O_DIRECTORY` manually.
     let flags = OFlags::DIRECTORY | target_o_path();
 
-    fs::OpenOptions::new()
-        .read(true)
-        .custom_flags(flags.bits() as i32)
-        .open(&path)
+    let mut options = fs::OpenOptions::new();
+    options.read(true);
+
+    #[cfg(not(target_os = "wasi"))]
+    options.custom_flags(flags.bits() as i32);
+
+    options.open(&path)
 }
 
 /// Use `O_PATH` on platforms which have it, or none otherwise.
@@ -131,6 +134,7 @@ pub(crate) const fn target_o_path() -> OFlags {
         target_os = "macos",
         target_os = "netbsd",
         target_os = "openbsd",
+        target_os = "wasi",
     ))]
     {
         OFlags::empty()
diff --git a/cap-primitives/src/rustix/fs/file_path.rs b/cap-primitives/src/rustix/fs/file_path.rs
index 8e144878..211ec01b 100644
--- a/cap-primitives/src/rustix/fs/file_path.rs
+++ b/cap-primitives/src/rustix/fs/file_path.rs
@@ -6,8 +6,6 @@ use std::ffi::OsString;
 use std::fs;
 #[cfg(unix)]
 use std::os::unix::ffi::OsStringExt;
-#[cfg(target_os = "wasi")]
-use std::os::wasi::ffi::OsStringExt;
 use std::path::PathBuf;
 
 pub(crate) fn file_path_by_ttyname_or_seaching(file: &fs::File) -> Option<PathBuf> {
diff --git a/cap-primitives/src/rustix/fs/file_type_ext.rs b/cap-primitives/src/rustix/fs/file_type_ext.rs
index 868c3c46..64ca2a03 100644
--- a/cap-primitives/src/rustix/fs/file_type_ext.rs
+++ b/cap-primitives/src/rustix/fs/file_type_ext.rs
@@ -44,12 +44,16 @@ impl FileTypeExt {
             FileType::ext(Self::BlockDevice)
         } else if std.is_char_device() {
             FileType::ext(Self::CharDevice)
-        } else if std.is_fifo() {
-            FileType::ext(Self::Fifo)
-        } else if std.is_socket() {
-            FileType::ext(Self::Socket)
         } else {
-            FileType::unknown()
+            #[cfg(not(target_os = "wasi"))]
+            if std.is_fifo() {
+                return FileType::ext(Self::Fifo);
+            }
+            if std.is_socket() {
+                FileType::ext(Self::Socket)
+            } else {
+                FileType::unknown()
+            }
         }
     }
 
diff --git a/cap-primitives/src/rustix/fs/metadata_ext.rs b/cap-primitives/src/rustix/fs/metadata_ext.rs
index 2eb04646..6087121a 100644
--- a/cap-primitives/src/rustix/fs/metadata_ext.rs
+++ b/cap-primitives/src/rustix/fs/metadata_ext.rs
@@ -1,6 +1,7 @@
 #![allow(clippy::useless_conversion)]
 
-use crate::fs::{FileTypeExt, Metadata, PermissionsExt};
+use crate::fs::PermissionsExt;
+use crate::fs::{FileTypeExt, Metadata};
 use crate::time::{Duration, SystemClock, SystemTime};
 #[cfg(all(target_os = "linux", target_env = "gnu"))]
 use rustix::fs::{makedev, Statx};
@@ -12,20 +13,38 @@ use std::{fs, io};
 pub(crate) struct MetadataExt {
     dev: u64,
     ino: u64,
+    #[cfg(not(target_os = "wasi"))]
     mode: u32,
     nlink: u64,
+    #[cfg(not(target_os = "wasi"))]
     uid: u32,
+    #[cfg(not(target_os = "wasi"))]
     gid: u32,
+    #[cfg(not(target_os = "wasi"))]
     rdev: u64,
     size: u64,
+    #[cfg(not(target_os = "wasi"))]
     atime: i64,
+    #[cfg(not(target_os = "wasi"))]
     atime_nsec: i64,
+    #[cfg(not(target_os = "wasi"))]
     mtime: i64,
+    #[cfg(not(target_os = "wasi"))]
     mtime_nsec: i64,
+    #[cfg(not(target_os = "wasi"))]
     ctime: i64,
+    #[cfg(not(target_os = "wasi"))]
     ctime_nsec: i64,
+    #[cfg(not(target_os = "wasi"))]
     blksize: u64,
+    #[cfg(not(target_os = "wasi"))]
     blocks: u64,
+    #[cfg(target_os = "wasi")]
+    atim: u64,
+    #[cfg(target_os = "wasi")]
+    mtim: u64,
+    #[cfg(target_os = "wasi")]
+    ctim: u64,
 }
 
 impl MetadataExt {
@@ -46,20 +65,38 @@ impl MetadataExt {
         Self {
             dev: std.dev(),
             ino: std.ino(),
+            #[cfg(not(target_os = "wasi"))]
             mode: std.mode(),
             nlink: std.nlink(),
+            #[cfg(not(target_os = "wasi"))]
             uid: std.uid(),
+            #[cfg(not(target_os = "wasi"))]
             gid: std.gid(),
+            #[cfg(not(target_os = "wasi"))]
             rdev: std.rdev(),
             size: std.size(),
+            #[cfg(not(target_os = "wasi"))]
             atime: std.atime(),
+            #[cfg(not(target_os = "wasi"))]
             atime_nsec: std.atime_nsec(),
+            #[cfg(not(target_os = "wasi"))]
             mtime: std.mtime(),
+            #[cfg(not(target_os = "wasi"))]
             mtime_nsec: std.mtime_nsec(),
+            #[cfg(not(target_os = "wasi"))]
             ctime: std.ctime(),
+            #[cfg(not(target_os = "wasi"))]
             ctime_nsec: std.ctime_nsec(),
+            #[cfg(not(target_os = "wasi"))]
             blksize: std.blksize(),
+            #[cfg(not(target_os = "wasi"))]
             blocks: std.blocks(),
+            #[cfg(target_os = "wasi")]
+            atim: std.atim(),
+            #[cfg(target_os = "wasi")]
+            mtim: std.mtim(),
+            #[cfg(target_os = "wasi")]
+            ctim: std.ctim(),
         }
     }
 
@@ -69,14 +106,17 @@ impl MetadataExt {
         Metadata {
             file_type: FileTypeExt::from_raw_mode(stat.st_mode as RawMode),
             len: u64::try_from(stat.st_size).unwrap(),
+            #[cfg(not(target_os = "wasi"))]
             permissions: PermissionsExt::from_raw_mode(stat.st_mode as RawMode),
+            #[cfg(target_os = "wasi")]
+            permissions: PermissionsExt::default(),
 
-            #[cfg(not(target_os = "netbsd"))]
+            #[cfg(not(any(target_os = "netbsd", target_os = "wasi")))]
             modified: system_time_from_rustix(
                 stat.st_mtime.try_into().unwrap(),
                 stat.st_mtime_nsec as _,
             ),
-            #[cfg(not(target_os = "netbsd"))]
+            #[cfg(not(any(target_os = "netbsd", target_os = "wasi")))]
             accessed: system_time_from_rustix(
                 stat.st_atime.try_into().unwrap(),
                 stat.st_atime_nsec as _,
@@ -93,6 +133,11 @@ impl MetadataExt {
                 stat.st_atimensec as _,
             ),
 
+            #[cfg(target_os = "wasi")]
+            modified: system_time_from_rustix(stat.st_mtim.tv_sec, stat.st_mtim.tv_nsec as _),
+            #[cfg(target_os = "wasi")]
+            accessed: system_time_from_rustix(stat.st_atim.tv_sec, stat.st_atim.tv_nsec as _),
+
             #[cfg(any(
                 target_os = "freebsd",
                 target_os = "openbsd",
@@ -123,29 +168,53 @@ impl MetadataExt {
             ext: Self {
                 dev: u64::try_from(stat.st_dev).unwrap(),
                 ino: stat.st_ino.into(),
+                #[cfg(not(target_os = "wasi"))]
                 mode: u32::from(stat.st_mode),
                 nlink: u64::from(stat.st_nlink),
+                #[cfg(not(target_os = "wasi"))]
                 uid: stat.st_uid,
+                #[cfg(not(target_os = "wasi"))]
                 gid: stat.st_gid,
+                #[cfg(not(target_os = "wasi"))]
                 rdev: u64::try_from(stat.st_rdev).unwrap(),
                 size: u64::try_from(stat.st_size).unwrap(),
+                #[cfg(not(target_os = "wasi"))]
                 atime: i64::try_from(stat.st_atime).unwrap(),
-                #[cfg(not(target_os = "netbsd"))]
+                #[cfg(not(any(target_os = "netbsd", target_os = "wasi")))]
                 atime_nsec: stat.st_atime_nsec as _,
                 #[cfg(target_os = "netbsd")]
                 atime_nsec: stat.st_atimensec as _,
+                #[cfg(not(target_os = "wasi"))]
                 mtime: i64::try_from(stat.st_mtime).unwrap(),
-                #[cfg(not(target_os = "netbsd"))]
+                #[cfg(not(any(target_os = "netbsd", target_os = "wasi")))]
                 mtime_nsec: stat.st_mtime_nsec as _,
                 #[cfg(target_os = "netbsd")]
                 mtime_nsec: stat.st_mtimensec as _,
+                #[cfg(not(target_os = "wasi"))]
                 ctime: i64::try_from(stat.st_ctime).unwrap(),
-                #[cfg(not(target_os = "netbsd"))]
+                #[cfg(not(any(target_os = "netbsd", target_os = "wasi")))]
                 ctime_nsec: stat.st_ctime_nsec as _,
                 #[cfg(target_os = "netbsd")]
                 ctime_nsec: stat.st_ctimensec as _,
+                #[cfg(not(target_os = "wasi"))]
                 blksize: u64::try_from(stat.st_blksize).unwrap(),
+                #[cfg(not(target_os = "wasi"))]
                 blocks: u64::try_from(stat.st_blocks).unwrap(),
+                #[cfg(target_os = "wasi")]
+                atim: u64::try_from(
+                    stat.st_atim.tv_sec as u64 * 1000000000 + stat.st_atim.tv_nsec as u64,
+                )
+                .unwrap(),
+                #[cfg(target_os = "wasi")]
+                mtim: u64::try_from(
+                    stat.st_mtim.tv_sec as u64 * 1000000000 + stat.st_mtim.tv_nsec as u64,
+                )
+                .unwrap(),
+                #[cfg(target_os = "wasi")]
+                ctim: u64::try_from(
+                    stat.st_ctim.tv_sec as u64 * 1000000000 + stat.st_ctim.tv_nsec as u64,
+                )
+                .unwrap(),
             },
         }
     }
@@ -207,6 +276,7 @@ impl rustix::fs::MetadataExt for MetadataExt {
         self.ino
     }
 
+    #[cfg(not(target_os = "wasi"))]
     #[inline]
     fn mode(&self) -> u32 {
         self.mode
@@ -217,16 +287,19 @@ impl rustix::fs::MetadataExt for MetadataExt {
         self.nlink
     }
 
+    #[cfg(not(target_os = "wasi"))]
     #[inline]
     fn uid(&self) -> u32 {
         self.uid
     }
 
+    #[cfg(not(target_os = "wasi"))]
     #[inline]
     fn gid(&self) -> u32 {
         self.gid
     }
 
+    #[cfg(not(target_os = "wasi"))]
     #[inline]
     fn rdev(&self) -> u64 {
         self.rdev
@@ -237,43 +310,66 @@ impl rustix::fs::MetadataExt for MetadataExt {
         self.size
     }
 
+    #[cfg(not(target_os = "wasi"))]
     #[inline]
     fn atime(&self) -> i64 {
         self.atime
     }
 
+    #[cfg(not(target_os = "wasi"))]
     #[inline]
     fn atime_nsec(&self) -> i64 {
         self.atime_nsec
     }
 
+    #[cfg(not(target_os = "wasi"))]
     #[inline]
     fn mtime(&self) -> i64 {
         self.mtime
     }
 
+    #[cfg(not(target_os = "wasi"))]
     #[inline]
     fn mtime_nsec(&self) -> i64 {
         self.mtime_nsec
     }
 
+    #[cfg(not(target_os = "wasi"))]
     #[inline]
     fn ctime(&self) -> i64 {
         self.ctime
     }
 
+    #[cfg(not(target_os = "wasi"))]
     #[inline]
     fn ctime_nsec(&self) -> i64 {
         self.ctime_nsec
     }
 
+    #[cfg(not(target_os = "wasi"))]
     #[inline]
     fn blksize(&self) -> u64 {
         self.blksize
     }
 
+    #[cfg(not(target_os = "wasi"))]
     #[inline]
     fn blocks(&self) -> u64 {
         self.blocks
     }
+
+    #[cfg(target_os = "wasi")]
+    fn atim(&self) -> u64 {
+        self.atim
+    }
+
+    #[cfg(target_os = "wasi")]
+    fn mtim(&self) -> u64 {
+        self.mtim
+    }
+
+    #[cfg(target_os = "wasi")]
+    fn ctim(&self) -> u64 {
+        self.ctim
+    }
 }
diff --git a/cap-primitives/src/rustix/fs/mod.rs b/cap-primitives/src/rustix/fs/mod.rs
index 29e619a3..9dcd1e4a 100644
--- a/cap-primitives/src/rustix/fs/mod.rs
+++ b/cap-primitives/src/rustix/fs/mod.rs
@@ -1,6 +1,7 @@
 mod copy_impl;
 mod create_dir_unchecked;
 mod dir_entry_inner;
+#[cfg(not(target_os = "wasi"))]
 mod dir_options_ext;
 mod dir_utils;
 #[cfg(not(any(target_os = "android", target_os = "linux")))]
@@ -23,7 +24,7 @@ mod remove_file_unchecked;
 mod remove_open_dir_by_searching;
 mod rename_unchecked;
 mod reopen_impl;
-#[cfg(not(any(target_os = "android", target_os = "linux")))]
+#[cfg(not(any(target_os = "android", target_os = "linux", target_os = "wasi")))]
 mod set_permissions_impl;
 #[cfg(not(any(target_os = "android", target_os = "linux")))]
 mod set_times_impl;
@@ -62,8 +63,10 @@ pub(super) use file_path::file_path_by_ttyname_or_seaching;
     target_os = "ios"
 )))]
 pub(crate) use file_path::file_path_by_ttyname_or_seaching as file_path;
+#[cfg(not(any(target_os = "android", target_os = "linux", target_os = "wasi")))]
+pub(crate) use set_permissions_impl::set_permissions_impl;
 #[cfg(not(any(target_os = "android", target_os = "linux")))]
-pub(crate) use {set_permissions_impl::set_permissions_impl, set_times_impl::set_times_impl};
+pub(crate) use set_times_impl::set_times_impl;
 
 #[rustfmt::skip]
 pub(crate) use crate::fs::{
@@ -80,6 +83,7 @@ pub(crate) use crate::fs::{
 pub(crate) use copy_impl::copy_impl;
 pub(crate) use create_dir_unchecked::create_dir_unchecked;
 pub(crate) use dir_entry_inner::DirEntryInner;
+#[cfg(not(target_os = "wasi"))]
 pub(crate) use dir_options_ext::DirOptionsExt;
 pub(crate) use dir_utils::*;
 pub(crate) use file_type_ext::FileTypeExt;
diff --git a/cap-primitives/src/rustix/fs/oflags.rs b/cap-primitives/src/rustix/fs/oflags.rs
index a4259473..85ffbd2a 100644
--- a/cap-primitives/src/rustix/fs/oflags.rs
+++ b/cap-primitives/src/rustix/fs/oflags.rs
@@ -21,8 +21,11 @@ pub(in super::super) fn compute_oflags(options: &OpenOptions) -> io::Result<OFla
     }
     // Use `RWMODE` here instead of `ACCMODE` so that we preserve the `O_PATH`
     // flag.
-    oflags |= OFlags::from_bits(options.ext.custom_flags as _).expect("unrecognized OFlags")
-        & !OFlags::RWMODE;
+    #[cfg(not(target_os = "wasi"))]
+    {
+        oflags |= OFlags::from_bits(options.ext.custom_flags as _).expect("unrecognized OFlags")
+            & !OFlags::RWMODE;
+    }
     Ok(oflags)
 }
 
diff --git a/cap-primitives/src/rustix/fs/open_unchecked.rs b/cap-primitives/src/rustix/fs/open_unchecked.rs
index 5a82b06f..cf6daf34 100644
--- a/cap-primitives/src/rustix/fs/open_unchecked.rs
+++ b/cap-primitives/src/rustix/fs/open_unchecked.rs
@@ -17,7 +17,10 @@ pub(crate) fn open_unchecked(
     let oflags = compute_oflags(options).map_err(OpenUncheckedError::Other)?;
 
     #[allow(clippy::useless_conversion)]
+    #[cfg(not(target_os = "wasi"))]
     let mode = Mode::from_bits_truncate(options.ext.mode as _);
+    #[cfg(target_os = "wasi")]
+    let mode = Mode::empty();
 
     let err = match openat(start, path, oflags, mode) {
         Ok(file) => {
diff --git a/cap-primitives/src/rustix/fs/permissions_ext.rs b/cap-primitives/src/rustix/fs/permissions_ext.rs
index e0855ab9..ffbec959 100644
--- a/cap-primitives/src/rustix/fs/permissions_ext.rs
+++ b/cap-primitives/src/rustix/fs/permissions_ext.rs
@@ -4,9 +4,11 @@ use std::fs;
 
 #[derive(Debug, Clone, Eq, PartialEq)]
 pub(crate) struct PermissionsExt {
+    #[cfg(not(target_os = "wasi"))]
     mode: RawMode,
 }
 
+#[cfg(not(target_os = "wasi"))]
 impl PermissionsExt {
     /// Constructs a new instance of `Self` from the given
     /// [`std::fs::Permissions`].
@@ -49,6 +51,7 @@ impl PermissionsExt {
     }
 }
 
+#[cfg(not(target_os = "wasi"))]
 impl std::os::unix::fs::PermissionsExt for PermissionsExt {
     fn mode(&self) -> u32 {
         self.mode as u32
@@ -64,3 +67,10 @@ impl std::os::unix::fs::PermissionsExt for PermissionsExt {
         }
     }
 }
+
+#[cfg(target_os = "wasi")]
+impl PermissionsExt {
+    pub(crate) fn default() -> Permissions {
+        Permissions { readonly: false }
+    }
+}
diff --git a/cap-std/src/fs/dir.rs b/cap-std/src/fs/dir.rs
index 6e3e245c..e02a4d48 100644
--- a/cap-std/src/fs/dir.rs
+++ b/cap-std/src/fs/dir.rs
@@ -1,10 +1,12 @@
 use crate::fs::{DirBuilder, File, Metadata, OpenOptions, ReadDir};
 #[cfg(unix)]
 use crate::os::unix::net::{UnixDatagram, UnixListener, UnixStream};
+#[cfg(not(target_os = "wasi"))]
+use cap_primitives::fs::set_permissions;
 use cap_primitives::fs::{
     canonicalize, copy, create_dir, hard_link, open, open_ambient_dir, open_dir, open_parent_dir,
     read_base_dir, read_dir, read_link, remove_dir, remove_dir_all, remove_file, remove_open_dir,
-    remove_open_dir_all, rename, set_permissions, stat, DirOptions, FollowSymlinks, Permissions,
+    remove_open_dir_all, rename, stat, DirOptions, FollowSymlinks, Permissions,
 };
 use cap_primitives::AmbientAuthority;
 #[cfg(not(windows))]
@@ -125,6 +127,7 @@ impl Dir {
     /// builder.
     ///
     /// This corresponds to [`std::fs::DirBuilder::create`].
+    #[cfg(not(target_os = "wasi"))]
     #[inline]
     pub fn create_dir_with<P: AsRef<Path>>(
         &self,
@@ -234,7 +237,7 @@ impl Dir {
     /// This corresponds to [`std::fs::metadata`], but only accesses paths
     /// relative to `self`.
     #[inline]
-    pub fn metadata<P: AsRef<Path>>(&self, path: P) -> io::Result<Metadata> {
+    pub fn metadata<P: AsRef<Path>>(&self, path: P) -> io::Result<cap_primitives::fs::Metadata> {
         stat(&self.std_file, path.as_ref(), FollowSymlinks::Yes)
     }
 
@@ -364,6 +367,7 @@ impl Dir {
     /// paths relative to `self`. Also, on some platforms, this function
     /// may fail if the file or directory cannot be opened for reading or
     /// writing first.
+    #[cfg(not(target_os = "wasi"))]
     #[inline]
     pub fn set_permissions<P: AsRef<Path>>(&self, path: P, perm: Permissions) -> io::Result<()> {
         set_permissions(&self.std_file, path.as_ref(), perm)
diff --git a/cap-std/src/fs/file.rs b/cap-std/src/fs/file.rs
index 9e22e33f..9240b2ad 100644
--- a/cap-std/src/fs/file.rs
+++ b/cap-std/src/fs/file.rs
@@ -8,8 +8,6 @@ use io_lifetimes::{AsFd, BorrowedFd, FromFd, IntoFd, OwnedFd};
 #[cfg(windows)]
 use io_lifetimes::{AsHandle, BorrowedHandle, FromHandle, IntoHandle, OwnedHandle};
 use std::io::{self, IoSlice, IoSliceMut, Read, Seek, SeekFrom, Write};
-#[cfg(target_os = "wasi")]
-use std::path::Path;
 use std::path::Path;
 use std::{fmt, fs, process};
 #[cfg(windows)]
@@ -150,30 +148,16 @@ impl File {
     }
 }
 
-#[cfg(not(target_os = "wasi"))]
 #[inline]
 fn metadata_from(file: &fs::File) -> io::Result<Metadata> {
     Metadata::from_file(file)
 }
 
-#[cfg(target_os = "wasi")]
-#[inline]
-fn metadata_from(file: &fs::File) -> io::Result<Metadata> {
-    file.metadata()
-}
-
-#[cfg(not(target_os = "wasi"))]
 #[inline]
 fn permissions_into_std(file: &fs::File, permissions: Permissions) -> io::Result<fs::Permissions> {
     permissions.into_std(file)
 }
 
-#[cfg(target_os = "wasi")]
-#[inline]
-fn permissions_into_std(_file: &fs::File, permissions: Permissions) -> io::Result<fs::Permissions> {
-    permissions
-}
-
 #[cfg(not(windows))]
 impl FromRawFd for File {
     #[inline]
@@ -479,15 +463,25 @@ impl std::os::unix::fs::FileExt for File {
 #[cfg(target_os = "wasi")]
 impl std::os::wasi::fs::FileExt for File {
     #[inline]
-    fn read_at(&self, bufs: &mut [IoSliceMut], offset: u64) -> io::Result<usize> {
+    fn read_at(&self, bufs: &mut [u8], offset: u64) -> io::Result<usize> {
         self.std.read_at(bufs, offset)
     }
 
     #[inline]
-    fn write_at(&self, bufs: &[IoSlice], offset: u64) -> io::Result<usize> {
+    fn write_at(&self, bufs: &[u8], offset: u64) -> io::Result<usize> {
         self.std.write_at(bufs, offset)
     }
 
+    #[inline]
+    fn read_vectored_at(&self, bufs: &mut [IoSliceMut], offset: u64) -> io::Result<usize> {
+        self.std.read_vectored_at(bufs, offset)
+    }
+
+    #[inline]
+    fn write_vectored_at(&self, bufs: &[IoSlice], offset: u64) -> io::Result<usize> {
+        self.std.write_vectored_at(bufs, offset)
+    }
+
     #[inline]
     fn tell(&self) -> std::result::Result<u64, std::io::Error> {
         self.std.tell()
diff --git a/cap-std/src/fs/mod.rs b/cap-std/src/fs/mod.rs
index 29ff968e..e3ec3855 100644
--- a/cap-std/src/fs/mod.rs
+++ b/cap-std/src/fs/mod.rs
@@ -32,10 +32,5 @@ pub use dir_entry::DirEntry;
 pub use file::File;
 pub use read_dir::ReadDir;
 
-// Re-export things from `cap_primitives` that we can use as-is.
-#[cfg(not(target_os = "wasi"))]
+// Re-export types from `cap_primitives`.
 pub use cap_primitives::fs::{DirBuilder, FileType, Metadata, OpenOptions, Permissions};
-
-// Re-export things from `std` that we can use as-is.
-#[cfg(target_os = "wasi")]
-pub use std::fs::{DirBuilder, FileType, Metadata, OpenOptions, Permissions};
diff --git a/cap-std/src/fs_utf8/dir.rs b/cap-std/src/fs_utf8/dir.rs
index dc491fe7..b696a5e2 100644
--- a/cap-std/src/fs_utf8/dir.rs
+++ b/cap-std/src/fs_utf8/dir.rs
@@ -110,6 +110,7 @@ impl Dir {
     /// builder.
     ///
     /// This corresponds to [`std::fs::DirBuilder::create`].
+    #[cfg(not(target_os = "wasi"))]
     #[inline]
     pub fn create_dir_with<P: AsRef<Utf8Path>>(
         &self,
@@ -308,6 +309,7 @@ impl Dir {
     /// paths relative to `self`. Also, on some platforms, this function
     /// may fail if the file or directory cannot be opened for reading or
     /// writing first.
+    #[cfg(not(target_os = "wasi"))]
     pub fn set_permissions<P: AsRef<Utf8Path>>(
         &self,
         path: P,
diff --git a/cap-std/src/fs_utf8/file.rs b/cap-std/src/fs_utf8/file.rs
index 9315188a..a597dbad 100644
--- a/cap-std/src/fs_utf8/file.rs
+++ b/cap-std/src/fs_utf8/file.rs
@@ -462,13 +462,23 @@ impl std::os::unix::fs::FileExt for File {
 #[cfg(target_os = "wasi")]
 impl std::os::wasi::fs::FileExt for File {
     #[inline]
-    fn read_at(&self, bufs: &mut [IoSliceMut], offset: u64) -> io::Result<usize> {
-        self.cap_std.read_at(bufs, offset)
+    fn read_at(&self, buf: &mut [u8], offset: u64) -> io::Result<usize> {
+        self.cap_std.read_at(buf, offset)
+    }
+
+    #[inline]
+    fn write_at(&self, buf: &[u8], offset: u64) -> io::Result<usize> {
+        self.cap_std.write_at(buf, offset)
+    }
+
+    #[inline]
+    fn read_vectored_at(&self, bufs: &mut [IoSliceMut], offset: u64) -> io::Result<usize> {
+        self.cap_std.read_vectored_at(bufs, offset)
     }
 
     #[inline]
-    fn write_at(&self, bufs: &[IoSlice], offset: u64) -> io::Result<usize> {
-        self.cap_std.write_at(bufs, offset)
+    fn write_vectored_at(&self, bufs: &[IoSlice], offset: u64) -> io::Result<usize> {
+        self.cap_std.write_vectored_at(bufs, offset)
     }
 
     #[inline]
@@ -501,45 +511,39 @@ impl std::os::wasi::fs::FileExt for File {
     }
 
     #[inline]
-    fn create_directory<P: AsRef<Utf8Path>>(
-        &self,
-        dir: P,
-    ) -> std::result::Result<(), std::io::Error> {
-        let path = from_utf8(path)?;
-        self.cap_std.create_directory(dir)
+    fn create_directory<P: AsRef<Path>>(&self, path: P) -> std::result::Result<(), std::io::Error> {
+        let path = path.as_ref();
+        self.cap_std.create_directory(path)
     }
 
     #[inline]
-    fn read_link<P: AsRef<Utf8Path>>(
+    fn read_link<P: AsRef<Path>>(
         &self,
         path: P,
     ) -> std::result::Result<std::path::PathBuf, std::io::Error> {
-        let path = from_utf8(path)?;
+        let path = path.as_ref();
         self.cap_std.read_link(path)
     }
 
     #[inline]
-    fn metadata_at<P: AsRef<Utf8Path>>(
+    fn metadata_at<P: AsRef<Path>>(
         &self,
         lookup_flags: u32,
         path: P,
     ) -> std::result::Result<std::fs::Metadata, std::io::Error> {
-        let path = from_utf8(path)?;
+        let path = path.as_ref();
         self.cap_std.metadata_at(lookup_flags, path)
     }
 
     #[inline]
-    fn remove_file<P: AsRef<Utf8Path>>(&self, path: P) -> std::result::Result<(), std::io::Error> {
-        let path = from_utf8(path)?;
+    fn remove_file<P: AsRef<Path>>(&self, path: P) -> std::result::Result<(), std::io::Error> {
+        let path = path.as_ref();
         self.cap_std.remove_file(path)
     }
 
     #[inline]
-    fn remove_directory<P: AsRef<Utf8Path>>(
-        &self,
-        path: P,
-    ) -> std::result::Result<(), std::io::Error> {
-        let path = from_utf8(path)?;
+    fn remove_directory<P: AsRef<Path>>(&self, path: P) -> std::result::Result<(), std::io::Error> {
+        let path = path.as_ref();
         self.cap_std.remove_directory(path)
     }
 }