diff --git a/src/error.rs b/src/error.rs
index c7f742dd6b..bb62a6faf3 100644
--- a/src/error.rs
+++ b/src/error.rs
@@ -3,6 +3,7 @@ use crate::sys::errno_from_ioerror;
 use failure::Fail;
 use std::fmt;
 use std::num::TryFromIntError;
+use std::convert::Infallible;
 
 #[derive(Clone, Copy, Debug, Fail)]
 pub enum WasiError {
@@ -134,6 +135,12 @@ impl From<TryFromIntError> for Error {
     }
 }
 
+impl From<Infallible> for Error {
+    fn from(_: Infallible) -> Self {
+        unreachable!()
+    }
+}
+
 #[cfg(windows)]
 impl From<winx::winerror::WinError> for Error {
     fn from(err: winx::winerror::WinError) -> Self {
diff --git a/src/sys/unix/host_impl.rs b/src/sys/unix/host_impl.rs
index be11942c00..c93c1e786f 100644
--- a/src/sys/unix/host_impl.rs
+++ b/src/sys/unix/host_impl.rs
@@ -178,6 +178,7 @@ pub(crate) fn filetype_from_nix(sflags: nix::sys::stat::SFlag) -> host::__wasi_f
 pub(crate) fn filestat_from_nix(
     filestat: nix::sys::stat::FileStat,
 ) -> Result<host::__wasi_filestat_t> {
+    use std::convert::TryFrom;
     fn filestat_to_timestamp(secs: u64, nsecs: u64) -> Result<host::__wasi_timestamp_t> {
         secs.checked_mul(1_000_000_000)
             .and_then(|sec_nsec| sec_nsec.checked_add(nsecs))
@@ -185,8 +186,8 @@ pub(crate) fn filestat_from_nix(
     }
 
     let filetype = nix::sys::stat::SFlag::from_bits_truncate(filestat.st_mode);
-    let dev = host::__wasi_device_t::from(filestat.st_dev);
-    let ino = host::__wasi_inode_t::from(filestat.st_ino);
+    let dev = host::__wasi_device_t::try_from(filestat.st_dev)?;
+    let ino = host::__wasi_inode_t::try_from(filestat.st_ino)?;
     let st_atim = filestat_to_timestamp(filestat.st_atime as u64, filestat.st_atime_nsec as u64)?;
     let st_ctim = filestat_to_timestamp(filestat.st_ctime as u64, filestat.st_ctime_nsec as u64)?;
     let st_mtim = filestat_to_timestamp(filestat.st_mtime as u64, filestat.st_mtime_nsec as u64)?;
diff --git a/src/sys/windows/hostcalls_impl/fs.rs b/src/sys/windows/hostcalls_impl/fs.rs
index 93b04c144e..ec1c703f05 100644
--- a/src/sys/windows/hostcalls_impl/fs.rs
+++ b/src/sys/windows/hostcalls_impl/fs.rs
@@ -74,7 +74,7 @@ pub(crate) fn fd_advise(
         | host::__WASI_ADVICE_NOREUSE
         | host::__WASI_ADVICE_RANDOM
         | host::__WASI_ADVICE_NORMAL => {}
-        _ => return Err(host::__WASI_EINVAL),
+        _ => return Err(Error::EINVAL),
     }
 
     Ok(())