diff --git a/src/hostcalls/fs.rs b/src/hostcalls/fs.rs
index f113123d21..6a8bc1ca95 100644
--- a/src/hostcalls/fs.rs
+++ b/src/hostcalls/fs.rs
@@ -308,7 +308,12 @@ pub fn fd_seek(
         Ok(fe) => fe,
         Err(e) => return return_enc_errno(e),
     };
-    let host_newoffset = match hostcalls_impl::fd_seek(fe, offset, whence) {
+    let file = match &*fe.fd_object.descriptor {
+        Descriptor::File(f) => f,
+        _ => return return_enc_errno(host::__WASI_EBADF),
+    };
+
+    let host_newoffset = match hostcalls_impl::fd_seek(file, offset, whence) {
         Ok(host_newoffset) => host_newoffset,
         Err(e) => return return_enc_errno(e),
     };
@@ -338,7 +343,12 @@ pub fn fd_tell(
         Ok(fe) => fe,
         Err(e) => return return_enc_errno(e),
     };
-    let host_offset = match hostcalls_impl::fd_tell(fe) {
+    let file = match &*fe.fd_object.descriptor {
+        Descriptor::File(f) => f,
+        _ => return return_enc_errno(host::__WASI_EBADF),
+    };
+
+    let host_offset = match hostcalls_impl::fd_tell(file) {
         Ok(host_offset) => host_offset,
         Err(e) => return return_enc_errno(e),
     };
@@ -367,24 +377,26 @@ pub fn fd_fdstat_get(
         Err(e) => return return_enc_errno(e),
     };
 
-    let ret = if let Some(fe) = wasi_ctx.fds.get(&host_fd) {
-        host_fdstat.fs_filetype = fe.fd_object.file_type;
-        host_fdstat.fs_rights_base = fe.rights_base;
-        host_fdstat.fs_rights_inheriting = fe.rights_inheriting;
-        host_fdstat.fs_flags = match hostcalls_impl::fd_fdstat_get(fe) {
-            Ok(flags) => flags,
-            Err(e) => return return_enc_errno(e),
-        };
-        host::__WASI_ESUCCESS
-    } else {
-        host::__WASI_EBADF
+    let fe = match wasi_ctx.fds.get(&host_fd) {
+        Some(fe) => fe,
+        None => return return_enc_errno(host::__WASI_EBADF),
     };
 
+    let fs_flags = match hostcalls_impl::fd_fdstat_get(fe) {
+        Ok(flags) => flags,
+        Err(e) => return return_enc_errno(e),
+    };
+
+    host_fdstat.fs_filetype = fe.fd_object.file_type;
+    host_fdstat.fs_rights_base = fe.rights_base;
+    host_fdstat.fs_rights_inheriting = fe.rights_inheriting;
+    host_fdstat.fs_flags = fs_flags;
+
     trace!("     | *buf={:?}", host_fdstat);
 
-    if let Err(e) = enc_fdstat_byref(memory, fdstat_ptr, host_fdstat) {
-        return return_enc_errno(e);
-    }
+    let ret = enc_fdstat_byref(memory, fdstat_ptr, host_fdstat)
+        .map(|_| host::__WASI_ESUCCESS)
+        .unwrap_or_else(identity);
 
     return_enc_errno(ret)
 }
@@ -534,16 +546,21 @@ pub fn fd_advise(
     );
 
     let host_fd = dec_fd(fd);
+    let advice = dec_advice(advice);
+    let offset = dec_filesize(offset);
+    let len = dec_filesize(len);
     let rights = host::__WASI_RIGHT_FD_ADVISE;
+
     let fe = match wasi_ctx.get_fd_entry(host_fd, rights, 0) {
         Ok(fe) => fe,
         Err(e) => return return_enc_errno(e),
     };
-    let advice = dec_advice(advice);
-    let offset = dec_filesize(offset);
-    let len = dec_filesize(len);
+    let file = match &*fe.fd_object.descriptor {
+        Descriptor::File(f) => f,
+        _ => return return_enc_errno(host::__WASI_EBADF),
+    };
 
-    let ret = match hostcalls_impl::fd_advise(fe, advice, offset, len) {
+    let ret = match hostcalls_impl::fd_advise(file, advice, offset, len) {
         Ok(()) => host::__WASI_ESUCCESS,
         Err(e) => e,
     };
diff --git a/src/sys/unix/hostcalls_impl/fs.rs b/src/sys/unix/hostcalls_impl/fs.rs
index 3f8749fa74..ba8768ee04 100644
--- a/src/sys/unix/hostcalls_impl/fs.rs
+++ b/src/sys/unix/hostcalls_impl/fs.rs
@@ -28,7 +28,7 @@ pub(crate) fn fd_pwrite(file: &File, buf: &[u8], offset: host::__wasi_filesize_t
 }
 
 pub(crate) fn fd_seek(
-    fd_entry: &FdEntry,
+    file: &File,
     offset: host::__wasi_filedelta_t,
     whence: host::__wasi_whence_t,
 ) -> Result<u64> {
@@ -40,19 +40,15 @@ pub(crate) fn fd_seek(
         _ => return Err(host::__WASI_EINVAL),
     };
 
-    let rawfd = fd_entry.fd_object.descriptor.as_raw_fd();
-
-    match lseek(rawfd, offset, nwhence) {
+    match lseek(file.as_raw_fd(), offset, nwhence) {
         Ok(offset) => Ok(offset as u64),
         Err(e) => Err(host_impl::errno_from_nix(e.as_errno().unwrap())),
     }
 }
 
-pub(crate) fn fd_tell(fd_entry: &FdEntry) -> Result<u64> {
+pub(crate) fn fd_tell(file: &File) -> Result<u64> {
     use nix::unistd::{lseek, Whence};
-
-    let rawfd = fd_entry.fd_object.descriptor.as_raw_fd();
-    match lseek(rawfd, 0, Whence::SeekCur) {
+    match lseek(file.as_raw_fd(), 0, Whence::SeekCur) {
         Ok(newoffset) => Ok(newoffset as u64),
         Err(e) => Err(host_impl::errno_from_nix(e.as_errno().unwrap())),
     }
@@ -60,7 +56,6 @@ pub(crate) fn fd_tell(fd_entry: &FdEntry) -> Result<u64> {
 
 pub(crate) fn fd_fdstat_get(fd_entry: &FdEntry) -> Result<host::__wasi_fdflags_t> {
     use nix::fcntl::{fcntl, OFlag, F_GETFL};
-
     let rawfd = fd_entry.fd_object.descriptor.as_raw_fd();
     match fcntl(rawfd, F_GETFL).map(OFlag::from_bits_truncate) {
         Ok(flags) => Ok(host_impl::fdflags_from_nix(flags)),
@@ -81,7 +76,7 @@ pub(crate) fn fd_fdstat_set_flags(
 }
 
 pub(crate) fn fd_advise(
-    fd_entry: &FdEntry,
+    file: &File,
     advice: host::__wasi_advice_t,
     offset: host::__wasi_filesize_t,
     len: host::__wasi_filesize_t,
@@ -97,8 +92,9 @@ pub(crate) fn fd_advise(
             host::__WASI_ADVICE_NORMAL => libc::POSIX_FADV_NORMAL,
             _ => return Err(host::__WASI_EINVAL),
         };
-        let rawfd = fd_entry.fd_object.descriptor.as_raw_fd();
-        let res = unsafe { libc::posix_fadvise(rawfd, offset as off_t, len as off_t, host_advice) };
+        let res = unsafe {
+            libc::posix_fadvise(file.as_raw_fd(), offset as off_t, len as off_t, host_advice)
+        };
         if res != 0 {
             return Err(host_impl::errno_from_nix(nix::errno::Errno::last()));
         }
@@ -106,7 +102,7 @@ pub(crate) fn fd_advise(
 
     #[cfg(not(target_os = "linux"))]
     {
-        let _ = (fd_entry, offset, len);
+        let _ = (file, offset, len);
         match advice {
             host::__WASI_ADVICE_DONTNEED
             | host::__WASI_ADVICE_SEQUENTIAL
diff --git a/src/sys/windows/hostcalls_impl/fs.rs b/src/sys/windows/hostcalls_impl/fs.rs
index 408cddaa3e..5bd41f4080 100644
--- a/src/sys/windows/hostcalls_impl/fs.rs
+++ b/src/sys/windows/hostcalls_impl/fs.rs
@@ -47,20 +47,19 @@ pub(crate) fn fd_pwrite(file: &File, buf: &[u8], offset: host::__wasi_filesize_t
 }
 
 pub(crate) fn fd_seek(
-    fd_entry: &FdEntry,
+    file: &File,
     offset: host::__wasi_filedelta_t,
     whence: host::__wasi_whence_t,
 ) -> Result<u64> {
     unimplemented!("fd_seek")
 }
 
-pub(crate) fn fd_tell(fd_entry: &FdEntry) -> Result<u64> {
+pub(crate) fn fd_tell(file: &File) -> Result<u64> {
     unimplemented!("fd_tell")
 }
 
 pub(crate) fn fd_fdstat_get(fd_entry: &FdEntry) -> Result<host::__wasi_fdflags_t> {
     use winx::file::AccessRight;
-
     let raw_handle = fd_entry.fd_object.descriptor.as_raw_handle();
     match winx::file::get_file_access_rights(raw_handle).map(AccessRight::from_bits_truncate) {
         Ok(rights) => Ok(host_impl::fdflags_from_win(rights)),
@@ -76,7 +75,7 @@ pub(crate) fn fd_fdstat_set_flags(
 }
 
 pub(crate) fn fd_advise(
-    fd_entry: &FdEntry,
+    file: &File,
     advice: host::__wasi_advice_t,
     offset: host::__wasi_filesize_t,
     len: host::__wasi_filesize_t,