diff --git a/.cargo/config b/.cargo/config.toml
similarity index 100%
rename from .cargo/config
rename to .cargo/config.toml
diff --git a/src/error.rs b/src/error.rs
deleted file mode 100644
index a5d87b6..0000000
--- a/src/error.rs
+++ /dev/null
@@ -1,5 +0,0 @@
-use std::io;
-
-pub fn io_err_other<E: ToString>(e: E) -> io::Error {
-    io::Error::new(io::ErrorKind::Other, e.to_string())
-}
diff --git a/src/io/cmsg.rs b/src/io/cmsg.rs
index af084e3..e13cbce 100644
--- a/src/io/cmsg.rs
+++ b/src/io/cmsg.rs
@@ -16,7 +16,7 @@ pub fn buffer<T: Sized>() -> Vec<u8> {
     let capacity = capacity::<T>();
     unsafe {
         let data = std::alloc::alloc(std::alloc::Layout::array::<u8>(capacity).unwrap());
-        Vec::from_raw_parts(data as *mut u8, capacity, capacity)
+        Vec::from_raw_parts(data, capacity, capacity)
     }
 }
 
diff --git a/src/io/seq_packet.rs b/src/io/seq_packet.rs
index 14b7313..bb00930 100644
--- a/src/io/seq_packet.rs
+++ b/src/io/seq_packet.rs
@@ -116,7 +116,7 @@ impl SeqPacketSocket {
         let mut msg = AssertSendSync(libc::msghdr {
             msg_name: ptr::null_mut(),
             msg_namelen: 0,
-            msg_iov: iov.as_ptr() as _,
+            msg_iov: iov.as_mut_ptr() as _,
             msg_iovlen: iov.len(),
             msg_control: cmsg_buf.as_mut_ptr() as *mut std::ffi::c_void,
             msg_controllen: cmsg_buf.len(),
diff --git a/src/macros.rs b/src/macros.rs
index 1184eb0..8b4cc86 100644
--- a/src/macros.rs
+++ b/src/macros.rs
@@ -10,13 +10,13 @@ macro_rules! c_str {
 macro_rules! file_descriptor_type {
     ($type:ident) => {
         #[repr(transparent)]
-        pub struct $type(::std::os::unix::io::RawFd);
+        pub struct $type(::std::os::unix::io::OwnedFd);
 
         file_descriptor_impl!($type);
 
         impl ::std::os::unix::io::FromRawFd for $type {
             unsafe fn from_raw_fd(fd: ::std::os::unix::io::RawFd) -> Self {
-                Self(fd)
+                Self(unsafe { ::std::os::unix::io::FromRawFd::from_raw_fd(fd) })
             }
         }
     };
@@ -24,33 +24,21 @@ macro_rules! file_descriptor_type {
 
 macro_rules! file_descriptor_impl {
     ($type:ty) => {
-        impl Drop for $type {
-            fn drop(&mut self) {
-                if self.0 >= 0 {
-                    unsafe {
-                        libc::close(self.0);
-                    }
-                }
-            }
-        }
-
         impl ::std::os::unix::io::AsFd for $type {
             fn as_fd(&self) -> ::std::os::unix::io::BorrowedFd<'_> {
-                unsafe { ::std::os::unix::io::BorrowedFd::borrow_raw(self.0) }
+                ::std::os::unix::io::AsFd::as_fd(&self.0)
             }
         }
 
         impl ::std::os::unix::io::AsRawFd for $type {
             fn as_raw_fd(&self) -> ::std::os::unix::io::RawFd {
-                self.0
+                ::std::os::unix::io::AsRawFd::as_raw_fd(&self.0)
             }
         }
 
         impl ::std::os::unix::io::IntoRawFd for $type {
-            fn into_raw_fd(mut self) -> ::std::os::unix::io::RawFd {
-                let fd = self.0;
-                self.0 = -libc::EBADF;
-                fd
+            fn into_raw_fd(self) -> ::std::os::unix::io::RawFd {
+                ::std::os::unix::io::IntoRawFd::into_raw_fd(self.0)
             }
         }
     };
diff --git a/src/main.rs b/src/main.rs
index efd15ef..3fa1155 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -15,7 +15,6 @@ mod macros;
 pub mod apparmor;
 pub mod capability;
 pub mod client;
-pub mod error;
 pub mod fork;
 pub mod io;
 pub mod lxcseccomp;
diff --git a/src/nsfd.rs b/src/nsfd.rs
index 18f5e7d..7a587d7 100644
--- a/src/nsfd.rs
+++ b/src/nsfd.rs
@@ -4,7 +4,7 @@ use std::ffi::CStr;
 use std::io;
 use std::marker::PhantomData;
 use std::os::raw::c_int;
-use std::os::unix::io::RawFd;
+use std::os::unix::io::{AsRawFd, FromRawFd, RawFd};
 
 pub mod ns_type {
     pub trait NsType {
@@ -38,11 +38,11 @@ impl RawNsFd {
         let fd =
             c_try!(unsafe { libc::openat(fd, path.as_ptr(), libc::O_RDONLY | libc::O_CLOEXEC) });
 
-        Ok(Self(fd))
+        Ok(unsafe { Self::from_raw_fd(fd) })
     }
 
     pub fn setns(&self, ns_type: c_int) -> io::Result<()> {
-        c_try!(unsafe { libc::setns(self.0, ns_type) });
+        c_try!(unsafe { libc::setns(self.as_raw_fd(), ns_type) });
         Ok(())
     }
 }
diff --git a/src/process/id_map.rs b/src/process/id_map.rs
index d61d489..2f71953 100644
--- a/src/process/id_map.rs
+++ b/src/process/id_map.rs
@@ -26,7 +26,7 @@ impl IdMap {
     pub fn map_from(&self, id: u64) -> Option<u64> {
         for entry in self.0.iter() {
             if entry.ns <= id && entry.ns + entry.range > id {
-                return Some(id + entry.host);
+                return Some(entry.host + id - entry.ns);
             }
         }
 
diff --git a/src/process/pid_fd.rs b/src/process/pid_fd.rs
index 869c2b6..9dd5859 100644
--- a/src/process/pid_fd.rs
+++ b/src/process/pid_fd.rs
@@ -10,12 +10,11 @@ use anyhow::{bail, Error};
 use libc::pid_t;
 
 use crate::capability::Capabilities;
-use crate::error::io_err_other;
 use crate::nsfd::{ns_type, NsFd};
 
 use super::{CGroups, IdMap, IdMapEntry, ProcStatus, Uids, UserCaps};
 
-pub struct PidFd(RawFd, pid_t);
+pub struct PidFd(OwnedFd, pid_t);
 file_descriptor_impl!(PidFd);
 
 impl PidFd {
@@ -27,6 +26,7 @@ impl PidFd {
         let path = CString::new(format!("/proc/{pid}")).unwrap();
 
         let fd = c_try!(unsafe { libc::open(path.as_ptr(), libc::O_DIRECTORY | libc::O_CLOEXEC) });
+        let fd = unsafe { OwnedFd::from_raw_fd(fd) };
 
         Ok(Self(fd, pid))
     }
@@ -39,22 +39,22 @@ impl PidFd {
     /// fails if reading the pid from the pidfd's proc entry fails.
     pub unsafe fn try_from_fd(fd: OwnedFd) -> io::Result<Self> {
         #[allow(clippy::unnecessary_cast)] // pid_t is a type alias
-        let mut this = Self(fd.into_raw_fd(), -1 as pid_t);
+        let mut this = Self(fd, -1 as pid_t);
         let pid = this.read_pid()?;
         this.1 = pid;
         Ok(this)
     }
 
     pub fn mount_namespace(&self) -> io::Result<NsFd<ns_type::Mount>> {
-        NsFd::openat(self.0, c_str!("ns/mnt"))
+        NsFd::openat(self.0.as_raw_fd(), c_str!("ns/mnt"))
     }
 
     pub fn cgroup_namespace(&self) -> io::Result<NsFd<ns_type::Cgroup>> {
-        NsFd::openat(self.0, c_str!("ns/cgroup"))
+        NsFd::openat(self.0.as_raw_fd(), c_str!("ns/cgroup"))
     }
 
     pub fn user_namespace(&self) -> io::Result<NsFd<ns_type::User>> {
-        NsFd::openat(self.0, c_str!("ns/user"))
+        NsFd::openat(self.0.as_raw_fd(), c_str!("ns/user"))
     }
 
     fn fd(&self, path: &CStr, flags: c_int, mode: c_int) -> io::Result<OwnedFd> {
@@ -152,7 +152,7 @@ impl PidFd {
                 })?,
                 16,
             )
-            .map_err(io_err_other)
+            .map_err(io::Error::other)
         }
 
         #[inline]
@@ -163,7 +163,7 @@ impl PidFd {
                 })?,
                 8,
             )
-            .map_err(io_err_other)
+            .map_err(io::Error::other)
         }
 
         let mut ids = Uids::default();
diff --git a/src/tools.rs b/src/tools.rs
index d4be066..d356070 100644
--- a/src/tools.rs
+++ b/src/tools.rs
@@ -33,7 +33,7 @@ pub mod vec {
     pub unsafe fn uninitialized(len: usize) -> Vec<u8> {
         unsafe {
             let data = std::alloc::alloc(std::alloc::Layout::array::<u8>(len).unwrap());
-            Vec::from_raw_parts(data as *mut u8, len, len)
+            Vec::from_raw_parts(data, len, len)
         }
     }
 }