diff --git a/src/sys/uio.rs b/src/sys/uio.rs
index 03f2a3a8b8..5af1093070 100644
--- a/src/sys/uio.rs
+++ b/src/sys/uio.rs
@@ -2,56 +2,18 @@
 #![allow(improper_ctypes)]
 
 use {Errno, Result};
-use libc::{c_int, c_void, size_t, off_t};
+use libc::{self, c_int, c_void, size_t, off_t};
 use std::marker::PhantomData;
 use std::os::unix::io::RawFd;
 
-mod ffi {
-    use super::IoVec;
-    use libc::{ssize_t, c_int, size_t, off_t, c_void};
-    use std::os::unix::io::RawFd;
-
-    extern {
-        // vectorized version of write
-        // doc: http://man7.org/linux/man-pages/man2/writev.2.html
-        pub fn writev(fd: RawFd, iov: *const IoVec<&[u8]>, iovcnt: c_int) -> ssize_t;
-
-        // vectorized version of read
-        // doc: http://man7.org/linux/man-pages/man2/readv.2.html
-        pub fn readv(fd: RawFd, iov: *const IoVec<&mut [u8]>, iovcnt: c_int) -> ssize_t;
-
-        // vectorized write at a specified offset
-        // doc: http://man7.org/linux/man-pages/man2/pwritev.2.html
-        #[cfg(feature = "preadv_pwritev")]
-        pub fn pwritev(fd: RawFd, iov: *const IoVec<&[u8]>, iovcnt: c_int,
-                       offset: off_t) -> ssize_t;
-
-        // vectorized read at a specified offset
-        // doc: http://man7.org/linux/man-pages/man2/preadv.2.html
-        #[cfg(feature = "preadv_pwritev")]
-        pub fn preadv(fd: RawFd, iov: *const IoVec<&mut [u8]>, iovcnt: c_int,
-                      offset: off_t) -> ssize_t;
-
-        // write to a file at a specified offset
-        // doc: http://man7.org/linux/man-pages/man2/pwrite.2.html
-        pub fn pwrite(fd: RawFd, buf: *const c_void, nbyte: size_t,
-                      offset: off_t) -> ssize_t;
-
-        // read from a file at a specified offset
-        // doc: http://man7.org/linux/man-pages/man2/pread.2.html
-        pub fn pread(fd: RawFd, buf: *mut c_void, nbyte: size_t, offset: off_t)
-                     -> ssize_t;
-    }
-}
-
 pub fn writev(fd: RawFd, iov: &[IoVec<&[u8]>]) -> Result<usize> {
-    let res = unsafe { ffi::writev(fd, iov.as_ptr(), iov.len() as c_int) };
+    let res = unsafe { libc::writev(fd, iov.as_ptr() as *const libc::iovec, iov.len() as c_int) };
 
     Errno::result(res).map(|r| r as usize)
 }
 
 pub fn readv(fd: RawFd, iov: &mut [IoVec<&mut [u8]>]) -> Result<usize> {
-    let res = unsafe { ffi::readv(fd, iov.as_ptr(), iov.len() as c_int) };
+    let res = unsafe { libc::readv(fd, iov.as_ptr() as *const libc::iovec, iov.len() as c_int) };
 
     Errno::result(res).map(|r| r as usize)
 }
@@ -60,7 +22,7 @@ pub fn readv(fd: RawFd, iov: &mut [IoVec<&mut [u8]>]) -> Result<usize> {
 pub fn pwritev(fd: RawFd, iov: &[IoVec<&[u8]>],
                offset: off_t) -> Result<usize> {
     let res = unsafe {
-        ffi::pwritev(fd, iov.as_ptr(), iov.len() as c_int, offset)
+        libc::pwritev(fd, iov.as_ptr() as *const libc::iovec, iov.len() as c_int, offset)
     };
 
     Errno::result(res).map(|r| r as usize)
@@ -70,7 +32,7 @@ pub fn pwritev(fd: RawFd, iov: &[IoVec<&[u8]>],
 pub fn preadv(fd: RawFd, iov: &mut [IoVec<&mut [u8]>],
               offset: off_t) -> Result<usize> {
     let res = unsafe {
-        ffi::preadv(fd, iov.as_ptr(), iov.len() as c_int, offset)
+        libc::preadv(fd, iov.as_ptr() as *const libc::iovec, iov.len() as c_int, offset)
     };
 
     Errno::result(res).map(|r| r as usize)
@@ -78,7 +40,7 @@ pub fn preadv(fd: RawFd, iov: &mut [IoVec<&mut [u8]>],
 
 pub fn pwrite(fd: RawFd, buf: &[u8], offset: off_t) -> Result<usize> {
     let res = unsafe {
-        ffi::pwrite(fd, buf.as_ptr() as *const c_void, buf.len() as size_t,
+        libc::pwrite(fd, buf.as_ptr() as *const c_void, buf.len() as size_t,
                     offset)
     };
 
@@ -87,7 +49,7 @@ pub fn pwrite(fd: RawFd, buf: &[u8], offset: off_t) -> Result<usize> {
 
 pub fn pread(fd: RawFd, buf: &mut [u8], offset: off_t) -> Result<usize>{
     let res = unsafe {
-        ffi::pread(fd, buf.as_mut_ptr() as *mut c_void, buf.len() as size_t,
+        libc::pread(fd, buf.as_mut_ptr() as *mut c_void, buf.len() as size_t,
                    offset)
     };
 
@@ -95,11 +57,7 @@ pub fn pread(fd: RawFd, buf: &mut [u8], offset: off_t) -> Result<usize>{
 }
 
 #[repr(C)]
-pub struct IoVec<T> {
-    iov_base: *mut c_void,
-    iov_len: size_t,
-    phantom: PhantomData<T>
-}
+pub struct IoVec<T>(libc::iovec, PhantomData<T>); 
 
 impl<T> IoVec<T> {
     #[inline]
@@ -108,29 +66,27 @@ impl<T> IoVec<T> {
 
         unsafe {
             slice::from_raw_parts(
-                self.iov_base as *const u8,
-                self.iov_len as usize)
+                self.0.iov_base as *const u8,
+                self.0.iov_len as usize)
         }
     }
 }
 
 impl<'a> IoVec<&'a [u8]> {
     pub fn from_slice(buf: &'a [u8]) -> IoVec<&'a [u8]> {
-        IoVec {
+        IoVec(libc::iovec {
             iov_base: buf.as_ptr() as *mut c_void,
             iov_len: buf.len() as size_t,
-            phantom: PhantomData
-        }
+        }, PhantomData)
     }
 }
 
 impl<'a> IoVec<&'a mut [u8]> {
     pub fn from_mut_slice(buf: &'a mut [u8]) -> IoVec<&'a mut [u8]> {
-        IoVec {
+        IoVec(libc::iovec {
             iov_base: buf.as_ptr() as *mut c_void,
             iov_len: buf.len() as size_t,
-            phantom: PhantomData
-        }
+        }, PhantomData)
     }
 }