diff --git a/src/ctx.rs b/src/ctx.rs
index fa084709e3..434dcedf2c 100644
--- a/src/ctx.rs
+++ b/src/ctx.rs
@@ -163,11 +163,11 @@ impl WasiCtx {
             .and_then(|ctx| ctx.build())
     }
 
-    pub(crate) fn contains_fd_entry(&self, fd: host::__wasi_fd_t) -> bool {
+    pub(crate) unsafe fn contains_fd_entry(&self, fd: host::__wasi_fd_t) -> bool {
         self.fds.contains_key(&fd)
     }
 
-    pub(crate) fn get_fd_entry(
+    pub(crate) unsafe fn get_fd_entry(
         &self,
         fd: host::__wasi_fd_t,
         rights_base: host::__wasi_rights_t,
@@ -180,7 +180,7 @@ impl WasiCtx {
         }
     }
 
-    pub(crate) fn get_fd_entry_mut(
+    pub(crate) unsafe fn get_fd_entry_mut(
         &mut self,
         fd: host::__wasi_fd_t,
         rights_base: host::__wasi_rights_t,
diff --git a/src/hostcalls/fs.rs b/src/hostcalls/fs.rs
index 49c67981de..8c9de34b82 100644
--- a/src/hostcalls/fs.rs
+++ b/src/hostcalls/fs.rs
@@ -3,11 +3,11 @@ use crate::ctx::WasiCtx;
 use crate::wasm32;
 
 hostcalls! {
-    pub fn fd_close(wasi_ctx: &mut WasiCtx, fd: wasm32::__wasi_fd_t,) -> wasm32::__wasi_errno_t;
+    pub unsafe fn fd_close(wasi_ctx: &mut WasiCtx, fd: wasm32::__wasi_fd_t,) -> wasm32::__wasi_errno_t;
 
-    pub fn fd_datasync(wasi_ctx: &WasiCtx, fd: wasm32::__wasi_fd_t,) -> wasm32::__wasi_errno_t;
+    pub unsafe fn fd_datasync(wasi_ctx: &WasiCtx, fd: wasm32::__wasi_fd_t,) -> wasm32::__wasi_errno_t;
 
-    pub fn fd_pread(
+    pub unsafe fn fd_pread(
         wasi_ctx: &WasiCtx,
         memory: &mut [u8],
         fd: wasm32::__wasi_fd_t,
@@ -17,7 +17,7 @@ hostcalls! {
         nread: wasm32::uintptr_t,
     ) -> wasm32::__wasi_errno_t;
 
-    pub fn fd_pwrite(
+    pub unsafe fn fd_pwrite(
         wasi_ctx: &WasiCtx,
         memory: &mut [u8],
         fd: wasm32::__wasi_fd_t,
@@ -27,7 +27,7 @@ hostcalls! {
         nwritten: wasm32::uintptr_t,
     ) -> wasm32::__wasi_errno_t;
 
-    pub fn fd_read(
+    pub unsafe fn fd_read(
         wasi_ctx: &mut WasiCtx,
         memory: &mut [u8],
         fd: wasm32::__wasi_fd_t,
@@ -36,13 +36,13 @@ hostcalls! {
         nread: wasm32::uintptr_t,
     ) -> wasm32::__wasi_errno_t;
 
-    pub fn fd_renumber(
+    pub unsafe fn fd_renumber(
         wasi_ctx: &mut WasiCtx,
         from: wasm32::__wasi_fd_t,
         to: wasm32::__wasi_fd_t,
     ) -> wasm32::__wasi_errno_t;
 
-    pub fn fd_seek(
+    pub unsafe fn fd_seek(
         wasi_ctx: &mut WasiCtx,
         memory: &mut [u8],
         fd: wasm32::__wasi_fd_t,
@@ -51,36 +51,36 @@ hostcalls! {
         newoffset: wasm32::uintptr_t,
     ) -> wasm32::__wasi_errno_t;
 
-    pub fn fd_tell(
+    pub unsafe fn fd_tell(
         wasi_ctx: &mut WasiCtx,
         memory: &mut [u8],
         fd: wasm32::__wasi_fd_t,
         newoffset: wasm32::uintptr_t,
     ) -> wasm32::__wasi_errno_t;
 
-    pub fn fd_fdstat_get(
+    pub unsafe fn fd_fdstat_get(
         wasi_ctx: &WasiCtx,
         memory: &mut [u8],
         fd: wasm32::__wasi_fd_t,
         fdstat_ptr: wasm32::uintptr_t,
     ) -> wasm32::__wasi_errno_t;
 
-    pub fn fd_fdstat_set_flags(
+    pub unsafe fn fd_fdstat_set_flags(
         wasi_ctx: &WasiCtx,
         fd: wasm32::__wasi_fd_t,
         fdflags: wasm32::__wasi_fdflags_t,
     ) -> wasm32::__wasi_errno_t;
 
-    pub fn fd_fdstat_set_rights(
+    pub unsafe fn fd_fdstat_set_rights(
         wasi_ctx: &mut WasiCtx,
         fd: wasm32::__wasi_fd_t,
         fs_rights_base: wasm32::__wasi_rights_t,
         fs_rights_inheriting: wasm32::__wasi_rights_t,
     ) -> wasm32::__wasi_errno_t;
 
-    pub fn fd_sync(wasi_ctx: &WasiCtx, fd: wasm32::__wasi_fd_t,) -> wasm32::__wasi_errno_t;
+    pub unsafe fn fd_sync(wasi_ctx: &WasiCtx, fd: wasm32::__wasi_fd_t,) -> wasm32::__wasi_errno_t;
 
-    pub fn fd_write(
+    pub unsafe fn fd_write(
         wasi_ctx: &mut WasiCtx,
         memory: &mut [u8],
         fd: wasm32::__wasi_fd_t,
@@ -89,7 +89,7 @@ hostcalls! {
         nwritten: wasm32::uintptr_t,
     ) -> wasm32::__wasi_errno_t;
 
-    pub fn fd_advise(
+    pub unsafe fn fd_advise(
         wasi_ctx: &WasiCtx,
         fd: wasm32::__wasi_fd_t,
         offset: wasm32::__wasi_filesize_t,
@@ -97,14 +97,14 @@ hostcalls! {
         advice: wasm32::__wasi_advice_t,
     ) -> wasm32::__wasi_errno_t;
 
-    pub fn fd_allocate(
+    pub unsafe fn fd_allocate(
         wasi_ctx: &WasiCtx,
         fd: wasm32::__wasi_fd_t,
         offset: wasm32::__wasi_filesize_t,
         len: wasm32::__wasi_filesize_t,
     ) -> wasm32::__wasi_errno_t;
 
-    pub fn path_create_directory(
+    pub unsafe fn path_create_directory(
         wasi_ctx: &WasiCtx,
         memory: &mut [u8],
         dirfd: wasm32::__wasi_fd_t,
@@ -112,7 +112,7 @@ hostcalls! {
         path_len: wasm32::size_t,
     ) -> wasm32::__wasi_errno_t;
 
-    pub fn path_link(
+    pub unsafe fn path_link(
         wasi_ctx: &WasiCtx,
         memory: &mut [u8],
         old_dirfd: wasm32::__wasi_fd_t,
@@ -124,7 +124,7 @@ hostcalls! {
         new_path_len: wasm32::size_t,
     ) -> wasm32::__wasi_errno_t;
 
-    pub fn path_open(
+    pub unsafe fn path_open(
         wasi_ctx: &mut WasiCtx,
         memory: &mut [u8],
         dirfd: wasm32::__wasi_fd_t,
@@ -138,7 +138,7 @@ hostcalls! {
         fd_out_ptr: wasm32::uintptr_t,
     ) -> wasm32::__wasi_errno_t;
 
-    pub fn fd_readdir(
+    pub unsafe fn fd_readdir(
         wasi_ctx: &mut WasiCtx,
         memory: &mut [u8],
         fd: wasm32::__wasi_fd_t,
@@ -148,7 +148,7 @@ hostcalls! {
         buf_used: wasm32::uintptr_t,
     ) -> wasm32::__wasi_errno_t;
 
-    pub fn path_readlink(
+    pub unsafe fn path_readlink(
         wasi_ctx: &WasiCtx,
         memory: &mut [u8],
         dirfd: wasm32::__wasi_fd_t,
@@ -159,7 +159,7 @@ hostcalls! {
         buf_used: wasm32::uintptr_t,
     ) -> wasm32::__wasi_errno_t;
 
-    pub fn path_rename(
+    pub unsafe fn path_rename(
         wasi_ctx: &WasiCtx,
         memory: &mut [u8],
         old_dirfd: wasm32::__wasi_fd_t,
@@ -170,14 +170,14 @@ hostcalls! {
         new_path_len: wasm32::size_t,
     ) -> wasm32::__wasi_errno_t;
 
-    pub fn fd_filestat_get(
+    pub unsafe fn fd_filestat_get(
         wasi_ctx: &WasiCtx,
         memory: &mut [u8],
         fd: wasm32::__wasi_fd_t,
         filestat_ptr: wasm32::uintptr_t,
     ) -> wasm32::__wasi_errno_t;
 
-    pub fn fd_filestat_set_times(
+    pub unsafe fn fd_filestat_set_times(
         wasi_ctx: &WasiCtx,
         fd: wasm32::__wasi_fd_t,
         st_atim: wasm32::__wasi_timestamp_t,
@@ -185,13 +185,13 @@ hostcalls! {
         fst_flags: wasm32::__wasi_fstflags_t,
     ) -> wasm32::__wasi_errno_t;
 
-    pub fn fd_filestat_set_size(
+    pub unsafe fn fd_filestat_set_size(
         wasi_ctx: &WasiCtx,
         fd: wasm32::__wasi_fd_t,
         st_size: wasm32::__wasi_filesize_t,
     ) -> wasm32::__wasi_errno_t;
 
-    pub fn path_filestat_get(
+    pub unsafe fn path_filestat_get(
         wasi_ctx: &WasiCtx,
         memory: &mut [u8],
         dirfd: wasm32::__wasi_fd_t,
@@ -201,7 +201,7 @@ hostcalls! {
         filestat_ptr: wasm32::uintptr_t,
     ) -> wasm32::__wasi_errno_t;
 
-    pub fn path_filestat_set_times(
+    pub unsafe fn path_filestat_set_times(
         wasi_ctx: &WasiCtx,
         memory: &mut [u8],
         dirfd: wasm32::__wasi_fd_t,
@@ -213,7 +213,7 @@ hostcalls! {
         fst_flags: wasm32::__wasi_fstflags_t,
     ) -> wasm32::__wasi_errno_t;
 
-    pub fn path_symlink(
+    pub unsafe fn path_symlink(
         wasi_ctx: &WasiCtx,
         memory: &mut [u8],
         old_path_ptr: wasm32::uintptr_t,
@@ -223,7 +223,7 @@ hostcalls! {
         new_path_len: wasm32::size_t,
     ) -> wasm32::__wasi_errno_t;
 
-    pub fn path_unlink_file(
+    pub unsafe fn path_unlink_file(
         wasi_ctx: &WasiCtx,
         memory: &mut [u8],
         dirfd: wasm32::__wasi_fd_t,
@@ -231,7 +231,7 @@ hostcalls! {
         path_len: wasm32::size_t,
     ) -> wasm32::__wasi_errno_t;
 
-    pub fn path_remove_directory(
+    pub unsafe fn path_remove_directory(
         wasi_ctx: &WasiCtx,
         memory: &mut [u8],
         dirfd: wasm32::__wasi_fd_t,
@@ -239,14 +239,14 @@ hostcalls! {
         path_len: wasm32::size_t,
     ) -> wasm32::__wasi_errno_t;
 
-    pub fn fd_prestat_get(
+    pub unsafe fn fd_prestat_get(
         wasi_ctx: &WasiCtx,
         memory: &mut [u8],
         fd: wasm32::__wasi_fd_t,
         prestat_ptr: wasm32::uintptr_t,
     ) -> wasm32::__wasi_errno_t;
 
-    pub fn fd_prestat_dir_name(
+    pub unsafe fn fd_prestat_dir_name(
         wasi_ctx: &WasiCtx,
         memory: &mut [u8],
         fd: wasm32::__wasi_fd_t,
diff --git a/src/hostcalls/misc.rs b/src/hostcalls/misc.rs
index 2fb6b5baca..207d854f37 100644
--- a/src/hostcalls/misc.rs
+++ b/src/hostcalls/misc.rs
@@ -7,7 +7,7 @@ use log::trace;
 use wasi_common_cbindgen::wasi_common_cbindgen;
 
 #[wasi_common_cbindgen]
-pub fn proc_exit(rval: wasm32::__wasi_exitcode_t) {
+pub unsafe fn proc_exit(rval: wasm32::__wasi_exitcode_t) {
     trace!("proc_exit(rval={:?})", rval);
     // TODO: Rather than call std::process::exit here, we should trigger a
     // stack unwind similar to a trap.
@@ -15,7 +15,7 @@ pub fn proc_exit(rval: wasm32::__wasi_exitcode_t) {
 }
 
 #[wasi_common_cbindgen]
-pub fn proc_raise(
+pub unsafe fn proc_raise(
     _wasi_ctx: &WasiCtx,
     _memory: &mut [u8],
     _sig: wasm32::__wasi_signal_t,
@@ -24,54 +24,54 @@ pub fn proc_raise(
 }
 
 hostcalls! {
-    pub fn args_get(
+    pub unsafe fn args_get(
         wasi_ctx: &WasiCtx,
         memory: &mut [u8],
         argv_ptr: wasm32::uintptr_t,
         argv_buf: wasm32::uintptr_t,
     ) -> wasm32::__wasi_errno_t;
 
-    pub fn args_sizes_get(
+    pub unsafe fn args_sizes_get(
         wasi_ctx: &WasiCtx,
         memory: &mut [u8],
         argc_ptr: wasm32::uintptr_t,
         argv_buf_size_ptr: wasm32::uintptr_t,
     ) -> wasm32::__wasi_errno_t;
 
-    pub fn environ_get(
+    pub unsafe fn environ_get(
         wasi_ctx: &WasiCtx,
         memory: &mut [u8],
         environ_ptr: wasm32::uintptr_t,
         environ_buf: wasm32::uintptr_t,
     ) -> wasm32::__wasi_errno_t;
 
-    pub fn environ_sizes_get(
+    pub unsafe fn environ_sizes_get(
         wasi_ctx: &WasiCtx,
         memory: &mut [u8],
         environ_count_ptr: wasm32::uintptr_t,
         environ_size_ptr: wasm32::uintptr_t,
     ) -> wasm32::__wasi_errno_t;
 
-    pub fn random_get(
+    pub unsafe fn random_get(
         memory: &mut [u8],
         buf_ptr: wasm32::uintptr_t,
         buf_len: wasm32::size_t,
     ) -> wasm32::__wasi_errno_t;
 
-    pub fn clock_res_get(
+    pub unsafe fn clock_res_get(
         memory: &mut [u8],
         clock_id: wasm32::__wasi_clockid_t,
         resolution_ptr: wasm32::uintptr_t,
     ) -> wasm32::__wasi_errno_t;
 
-    pub fn clock_time_get(
+    pub unsafe fn clock_time_get(
         memory: &mut [u8],
         clock_id: wasm32::__wasi_clockid_t,
         precision: wasm32::__wasi_timestamp_t,
         time_ptr: wasm32::uintptr_t,
     ) -> wasm32::__wasi_errno_t;
 
-    pub fn poll_oneoff(
+    pub unsafe fn poll_oneoff(
         memory: &mut [u8],
         input: wasm32::uintptr_t,
         output: wasm32::uintptr_t,
@@ -79,5 +79,5 @@ hostcalls! {
         nevents: wasm32::uintptr_t,
     ) -> wasm32::__wasi_errno_t;
 
-    pub fn sched_yield() -> wasm32::__wasi_errno_t;
+    pub unsafe fn sched_yield() -> wasm32::__wasi_errno_t;
 }
diff --git a/src/hostcalls/sock.rs b/src/hostcalls/sock.rs
index ed8fb7c8bd..4cd37a8083 100644
--- a/src/hostcalls/sock.rs
+++ b/src/hostcalls/sock.rs
@@ -6,7 +6,7 @@ use crate::wasm32;
 use wasi_common_cbindgen::wasi_common_cbindgen;
 
 #[wasi_common_cbindgen]
-pub fn sock_recv(
+pub unsafe fn sock_recv(
     wasi_ctx: &WasiCtx,
     memory: &mut [u8],
     sock: wasm32::__wasi_fd_t,
@@ -20,7 +20,7 @@ pub fn sock_recv(
 }
 
 #[wasi_common_cbindgen]
-pub fn sock_send(
+pub unsafe fn sock_send(
     wasi_ctx: &WasiCtx,
     memory: &mut [u8],
     sock: wasm32::__wasi_fd_t,
@@ -33,7 +33,7 @@ pub fn sock_send(
 }
 
 #[wasi_common_cbindgen]
-pub fn sock_shutdown(
+pub unsafe fn sock_shutdown(
     wasi_ctx: &WasiCtx,
     memory: &mut [u8],
     sock: wasm32::__wasi_fd_t,
diff --git a/src/hostcalls_impl/fs.rs b/src/hostcalls_impl/fs.rs
index 53aaef865c..fabe04bd91 100644
--- a/src/hostcalls_impl/fs.rs
+++ b/src/hostcalls_impl/fs.rs
@@ -13,7 +13,7 @@ use std::fs::File;
 use std::io::{self, Read, Seek, SeekFrom, Write};
 use std::time::{Duration, SystemTime, UNIX_EPOCH};
 
-pub(crate) fn fd_close(wasi_ctx: &mut WasiCtx, fd: wasm32::__wasi_fd_t) -> Result<()> {
+pub(crate) unsafe fn fd_close(wasi_ctx: &mut WasiCtx, fd: wasm32::__wasi_fd_t) -> Result<()> {
     trace!("fd_close(fd={:?})", fd);
 
     let fd = dec_fd(fd);
@@ -30,7 +30,7 @@ pub(crate) fn fd_close(wasi_ctx: &mut WasiCtx, fd: wasm32::__wasi_fd_t) -> Resul
     Ok(())
 }
 
-pub(crate) fn fd_datasync(wasi_ctx: &WasiCtx, fd: wasm32::__wasi_fd_t) -> Result<()> {
+pub(crate) unsafe fn fd_datasync(wasi_ctx: &WasiCtx, fd: wasm32::__wasi_fd_t) -> Result<()> {
     trace!("fd_datasync(fd={:?})", fd);
 
     let fd = dec_fd(fd);
@@ -41,7 +41,7 @@ pub(crate) fn fd_datasync(wasi_ctx: &WasiCtx, fd: wasm32::__wasi_fd_t) -> Result
     fd.sync_data().map_err(Into::into)
 }
 
-pub(crate) fn fd_pread(
+pub(crate) unsafe fn fd_pread(
     wasi_ctx: &WasiCtx,
     memory: &mut [u8],
     fd: wasm32::__wasi_fd_t,
@@ -80,7 +80,7 @@ pub(crate) fn fd_pread(
             break;
         }
         let vec_len = std::cmp::min(iov.buf_len, left);
-        unsafe { std::slice::from_raw_parts_mut(iov.buf as *mut u8, vec_len) }
+        std::slice::from_raw_parts_mut(iov.buf as *mut u8, vec_len)
             .copy_from_slice(&buf[buf_offset..buf_offset + vec_len]);
         buf_offset += vec_len;
         left -= vec_len;
@@ -91,7 +91,7 @@ pub(crate) fn fd_pread(
     enc_usize_byref(memory, nread, host_nread)
 }
 
-pub(crate) fn fd_pwrite(
+pub(crate) unsafe fn fd_pwrite(
     wasi_ctx: &WasiCtx,
     memory: &mut [u8],
     fd: wasm32::__wasi_fd_t,
@@ -122,9 +122,10 @@ pub(crate) fn fd_pwrite(
     let buf_size = iovs.iter().map(|v| v.buf_len).sum();
     let mut buf = Vec::with_capacity(buf_size);
     for iov in &iovs {
-        buf.extend_from_slice(unsafe {
-            std::slice::from_raw_parts(iov.buf as *const u8, iov.buf_len)
-        });
+        buf.extend_from_slice(std::slice::from_raw_parts(
+            iov.buf as *const u8,
+            iov.buf_len,
+        ));
     }
     let host_nwritten = hostcalls_impl::fd_pwrite(fd, &buf, offset)?;
 
@@ -133,7 +134,7 @@ pub(crate) fn fd_pwrite(
     enc_usize_byref(memory, nwritten, host_nwritten)
 }
 
-pub(crate) fn fd_read(
+pub(crate) unsafe fn fd_read(
     wasi_ctx: &mut WasiCtx,
     memory: &mut [u8],
     fd: wasm32::__wasi_fd_t,
@@ -154,7 +155,7 @@ pub(crate) fn fd_read(
     let fe = wasi_ctx.get_fd_entry_mut(fd, host::__WASI_RIGHT_FD_READ, 0)?;
     let mut iovs: Vec<io::IoSliceMut> = iovs
         .iter_mut()
-        .map(|vec| unsafe { host::iovec_to_host_mut(vec) })
+        .map(|vec| host::iovec_to_host_mut(vec))
         .collect();
 
     let maybe_host_nread = match &mut *fe.fd_object.descriptor {
@@ -170,7 +171,7 @@ pub(crate) fn fd_read(
     enc_usize_byref(memory, nread, host_nread)
 }
 
-pub(crate) fn fd_renumber(
+pub(crate) unsafe fn fd_renumber(
     wasi_ctx: &mut WasiCtx,
     from: wasm32::__wasi_fd_t,
     to: wasm32::__wasi_fd_t,
@@ -211,7 +212,7 @@ pub(crate) fn fd_renumber(
     Ok(())
 }
 
-pub(crate) fn fd_seek(
+pub(crate) unsafe fn fd_seek(
     wasi_ctx: &mut WasiCtx,
     memory: &mut [u8],
     fd: wasm32::__wasi_fd_t,
@@ -253,7 +254,7 @@ pub(crate) fn fd_seek(
     enc_filesize_byref(memory, newoffset, host_newoffset)
 }
 
-pub(crate) fn fd_tell(
+pub(crate) unsafe fn fd_tell(
     wasi_ctx: &mut WasiCtx,
     memory: &mut [u8],
     fd: wasm32::__wasi_fd_t,
@@ -273,7 +274,7 @@ pub(crate) fn fd_tell(
     enc_filesize_byref(memory, newoffset, host_offset)
 }
 
-pub(crate) fn fd_fdstat_get(
+pub(crate) unsafe fn fd_fdstat_get(
     wasi_ctx: &WasiCtx,
     memory: &mut [u8],
     fd: wasm32::__wasi_fd_t,
@@ -298,7 +299,7 @@ pub(crate) fn fd_fdstat_get(
     enc_fdstat_byref(memory, fdstat_ptr, fdstat)
 }
 
-pub(crate) fn fd_fdstat_set_flags(
+pub(crate) unsafe fn fd_fdstat_set_flags(
     wasi_ctx: &WasiCtx,
     fd: wasm32::__wasi_fd_t,
     fdflags: wasm32::__wasi_fdflags_t,
@@ -314,7 +315,7 @@ pub(crate) fn fd_fdstat_set_flags(
     hostcalls_impl::fd_fdstat_set_flags(fd, fdflags)
 }
 
-pub(crate) fn fd_fdstat_set_rights(
+pub(crate) unsafe fn fd_fdstat_set_rights(
     wasi_ctx: &mut WasiCtx,
     fd: wasm32::__wasi_fd_t,
     fs_rights_base: wasm32::__wasi_rights_t,
@@ -341,7 +342,7 @@ pub(crate) fn fd_fdstat_set_rights(
     Ok(())
 }
 
-pub(crate) fn fd_sync(wasi_ctx: &WasiCtx, fd: wasm32::__wasi_fd_t) -> Result<()> {
+pub(crate) unsafe fn fd_sync(wasi_ctx: &WasiCtx, fd: wasm32::__wasi_fd_t) -> Result<()> {
     trace!("fd_sync(fd={:?})", fd);
 
     let fd = dec_fd(fd);
@@ -351,7 +352,7 @@ pub(crate) fn fd_sync(wasi_ctx: &WasiCtx, fd: wasm32::__wasi_fd_t) -> Result<()>
     fd.sync_all().map_err(Into::into)
 }
 
-pub(crate) fn fd_write(
+pub(crate) unsafe fn fd_write(
     wasi_ctx: &mut WasiCtx,
     memory: &mut [u8],
     fd: wasm32::__wasi_fd_t,
@@ -370,10 +371,7 @@ pub(crate) fn fd_write(
     let fd = dec_fd(fd);
     let iovs = dec_iovec_slice(memory, iovs_ptr, iovs_len)?;
     let fe = wasi_ctx.get_fd_entry_mut(fd, host::__WASI_RIGHT_FD_WRITE, 0)?;
-    let iovs: Vec<io::IoSlice> = iovs
-        .iter()
-        .map(|vec| unsafe { host::iovec_to_host(vec) })
-        .collect();
+    let iovs: Vec<io::IoSlice> = iovs.iter().map(|vec| host::iovec_to_host(vec)).collect();
 
     // perform unbuffered writes
     let host_nwritten = match &mut *fe.fd_object.descriptor {
@@ -395,7 +393,7 @@ pub(crate) fn fd_write(
     enc_usize_byref(memory, nwritten, host_nwritten)
 }
 
-pub(crate) fn fd_advise(
+pub(crate) unsafe fn fd_advise(
     wasi_ctx: &WasiCtx,
     fd: wasm32::__wasi_fd_t,
     offset: wasm32::__wasi_filesize_t,
@@ -421,7 +419,7 @@ pub(crate) fn fd_advise(
     hostcalls_impl::fd_advise(fd, advice, offset, len)
 }
 
-pub(crate) fn fd_allocate(
+pub(crate) unsafe fn fd_allocate(
     wasi_ctx: &WasiCtx,
     fd: wasm32::__wasi_fd_t,
     offset: wasm32::__wasi_filesize_t,
@@ -452,7 +450,7 @@ pub(crate) fn fd_allocate(
     }
 }
 
-pub(crate) fn path_create_directory(
+pub(crate) unsafe fn path_create_directory(
     wasi_ctx: &WasiCtx,
     memory: &mut [u8],
     dirfd: wasm32::__wasi_fd_t,
@@ -480,7 +478,7 @@ pub(crate) fn path_create_directory(
     hostcalls_impl::path_create_directory(resolved)
 }
 
-pub(crate) fn path_link(
+pub(crate) unsafe fn path_link(
     wasi_ctx: &WasiCtx,
     memory: &mut [u8],
     old_dirfd: wasm32::__wasi_fd_t,
@@ -524,7 +522,7 @@ pub(crate) fn path_link(
     hostcalls_impl::path_link(resolved_old, resolved_new)
 }
 
-pub(crate) fn path_open(
+pub(crate) unsafe fn path_open(
     wasi_ctx: &mut WasiCtx,
     memory: &mut [u8],
     dirfd: wasm32::__wasi_fd_t,
@@ -583,7 +581,7 @@ pub(crate) fn path_open(
     let fd = hostcalls_impl::path_open(resolved, read, write, oflags, fs_flags)?;
 
     // Determine the type of the new file descriptor and which rights contradict with this type
-    let (_ty, max_base, max_inheriting) = unsafe { determine_type_rights(&fd) }?;
+    let (_ty, max_base, max_inheriting) = determine_type_rights(&fd)?;
     let mut fe = FdEntry::from(fd)?;
     fe.rights_base &= max_base;
     fe.rights_inheriting &= max_inheriting;
@@ -594,7 +592,7 @@ pub(crate) fn path_open(
     enc_fd_byref(memory, fd_out_ptr, guest_fd)
 }
 
-pub(crate) fn fd_readdir(
+pub(crate) unsafe fn fd_readdir(
     wasi_ctx: &mut WasiCtx,
     memory: &mut [u8],
     fd: wasm32::__wasi_fd_t,
@@ -631,7 +629,7 @@ pub(crate) fn fd_readdir(
     enc_usize_byref(memory, buf_used, host_bufused)
 }
 
-pub(crate) fn path_readlink(
+pub(crate) unsafe fn path_readlink(
     wasi_ctx: &WasiCtx,
     memory: &mut [u8],
     dirfd: wasm32::__wasi_fd_t,
@@ -673,7 +671,7 @@ pub(crate) fn path_readlink(
     enc_usize_byref(memory, buf_used, host_bufused)
 }
 
-pub(crate) fn path_rename(
+pub(crate) unsafe fn path_rename(
     wasi_ctx: &WasiCtx,
     memory: &mut [u8],
     old_dirfd: wasm32::__wasi_fd_t,
@@ -715,7 +713,7 @@ pub(crate) fn path_rename(
     hostcalls_impl::path_rename(resolved_old, resolved_new)
 }
 
-pub(crate) fn fd_filestat_get(
+pub(crate) unsafe fn fd_filestat_get(
     wasi_ctx: &WasiCtx,
     memory: &mut [u8],
     fd: wasm32::__wasi_fd_t,
@@ -739,7 +737,7 @@ pub(crate) fn fd_filestat_get(
     enc_filestat_byref(memory, filestat_ptr, host_filestat)
 }
 
-pub(crate) fn fd_filestat_set_times(
+pub(crate) unsafe fn fd_filestat_set_times(
     wasi_ctx: &WasiCtx,
     fd: wasm32::__wasi_fd_t,
     st_atim: wasm32::__wasi_timestamp_t,
@@ -802,7 +800,7 @@ pub(crate) fn fd_filestat_set_times_impl(
     set_file_handle_times(fd, atim, mtim).map_err(Into::into)
 }
 
-pub(crate) fn fd_filestat_set_size(
+pub(crate) unsafe fn fd_filestat_set_size(
     wasi_ctx: &WasiCtx,
     fd: wasm32::__wasi_fd_t,
     st_size: wasm32::__wasi_filesize_t,
@@ -822,7 +820,7 @@ pub(crate) fn fd_filestat_set_size(
     fd.set_len(st_size).map_err(Into::into)
 }
 
-pub(crate) fn path_filestat_get(
+pub(crate) unsafe fn path_filestat_get(
     wasi_ctx: &WasiCtx,
     memory: &mut [u8],
     dirfd: wasm32::__wasi_fd_t,
@@ -857,7 +855,7 @@ pub(crate) fn path_filestat_get(
     enc_filestat_byref(memory, filestat_ptr, host_filestat)
 }
 
-pub(crate) fn path_filestat_set_times(
+pub(crate) unsafe fn path_filestat_set_times(
     wasi_ctx: &WasiCtx,
     memory: &mut [u8],
     dirfd: wasm32::__wasi_fd_t,
@@ -896,7 +894,7 @@ pub(crate) fn path_filestat_set_times(
     hostcalls_impl::path_filestat_set_times(resolved, dirflags, st_atim, st_mtim, fst_flags)
 }
 
-pub(crate) fn path_symlink(
+pub(crate) unsafe fn path_symlink(
     wasi_ctx: &WasiCtx,
     memory: &mut [u8],
     old_path_ptr: wasm32::uintptr_t,
@@ -931,7 +929,7 @@ pub(crate) fn path_symlink(
     hostcalls_impl::path_symlink(old_path, resolved_new)
 }
 
-pub(crate) fn path_unlink_file(
+pub(crate) unsafe fn path_unlink_file(
     wasi_ctx: &WasiCtx,
     memory: &mut [u8],
     dirfd: wasm32::__wasi_fd_t,
@@ -958,7 +956,7 @@ pub(crate) fn path_unlink_file(
     hostcalls_impl::path_unlink_file(resolved)
 }
 
-pub(crate) fn path_remove_directory(
+pub(crate) unsafe fn path_remove_directory(
     wasi_ctx: &WasiCtx,
     memory: &mut [u8],
     dirfd: wasm32::__wasi_fd_t,
@@ -985,7 +983,7 @@ pub(crate) fn path_remove_directory(
     hostcalls_impl::path_remove_directory(resolved)
 }
 
-pub(crate) fn fd_prestat_get(
+pub(crate) unsafe fn fd_prestat_get(
     wasi_ctx: &WasiCtx,
     memory: &mut [u8],
     fd: wasm32::__wasi_fd_t,
@@ -1024,7 +1022,7 @@ pub(crate) fn fd_prestat_get(
         })
 }
 
-pub(crate) fn fd_prestat_dir_name(
+pub(crate) unsafe fn fd_prestat_dir_name(
     wasi_ctx: &WasiCtx,
     memory: &mut [u8],
     fd: wasm32::__wasi_fd_t,
diff --git a/src/macros.rs b/src/macros.rs
index 04a3f231d5..23fb3bdc58 100644
--- a/src/macros.rs
+++ b/src/macros.rs
@@ -1,7 +1,7 @@
 macro_rules! hostcalls {
-    ($(pub fn $name:ident($($arg:ident: $ty:ty,)*) -> $ret:ty;)*) => ($(
+    ($(pub unsafe fn $name:ident($($arg:ident: $ty:ty,)*) -> $ret:ty;)*) => ($(
             #[wasi_common_cbindgen::wasi_common_cbindgen]
-            pub fn $name($($arg: $ty,)*) -> $ret {
+            pub unsafe fn $name($($arg: $ty,)*) -> $ret {
                 let ret = match crate::hostcalls_impl::$name($($arg,)*) {
                     Ok(()) => crate::host::__WASI_ESUCCESS,
                     Err(e) => e.as_wasi_errno(),