diff --git a/src/libnative/io/process.rs b/src/libnative/io/process.rs
index 3a6ae42f946..7a0c1c35d65 100644
--- a/src/libnative/io/process.rs
+++ b/src/libnative/io/process.rs
@@ -583,10 +583,11 @@ fn spawn_process_os(cfg: ProcessConfig,
                 let mut bytes = [0, ..4];
                 return match input.inner_read(bytes) {
                     Ok(4) => {
-                        let errno = (bytes[0] << 24) as i32 |
-                                    (bytes[1] << 16) as i32 |
-                                    (bytes[2] <<  8) as i32 |
-                                    (bytes[3] <<  0) as i32;
+                        let errno = (bytes[0] as i32 << 24) |
+                                    (bytes[1] as i32 << 16) |
+                                    (bytes[2] as i32 <<  8) |
+                                    (bytes[3] as i32 <<  0);
+
                         Err(IoError {
                             code: errno as uint,
                             detail: None,
@@ -637,10 +638,10 @@ fn spawn_process_os(cfg: ProcessConfig,
             fn fail(output: &mut file::FileDesc) -> ! {
                 let errno = os::errno();
                 let bytes = [
-                    (errno << 24) as u8,
-                    (errno << 16) as u8,
-                    (errno <<  8) as u8,
-                    (errno <<  0) as u8,
+                    (errno >> 24) as u8,
+                    (errno >> 16) as u8,
+                    (errno >>  8) as u8,
+                    (errno >>  0) as u8,
                 ];
                 assert!(output.inner_write(bytes).is_ok());
                 unsafe { libc::_exit(1) }
diff --git a/src/test/run-pass/unix-process-spawn-errno.rs b/src/test/run-pass/unix-process-spawn-errno.rs
new file mode 100644
index 00000000000..555bf2cd4c0
--- /dev/null
+++ b/src/test/run-pass/unix-process-spawn-errno.rs
@@ -0,0 +1,94 @@
+// Copyright 2014 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+// ignore-windows
+
+#![feature(macro_rules)]
+
+extern crate native;
+extern crate rustrt;
+extern crate libc;
+use libc::{c_char, c_int};
+use native::io::process;
+use rustrt::rtio;
+use rustrt::c_str;
+
+macro_rules! c_string {
+    ($s:expr) => { {
+        let ptr = concat!($s, "\0").as_ptr() as *const i8;
+        unsafe { &c_str::CString::new(ptr, false) }
+    } }
+}
+
+static EXPECTED_ERRNO: c_int = 0x778899aa;
+
+#[no_mangle]
+pub unsafe extern "C" fn chdir(_: *const c_char) -> c_int {
+    // copied from std::os::errno()
+    #[cfg(any(target_os = "macos",
+              target_os = "ios",
+              target_os = "freebsd"))]
+    fn errno_location() -> *mut c_int {
+        extern {
+            fn __error() -> *mut c_int;
+        }
+        unsafe {
+            __error()
+        }
+    }
+
+    #[cfg(target_os = "dragonfly")]
+    fn errno_location() -> *mut c_int {
+        extern {
+            fn __dfly_error() -> *mut c_int;
+        }
+        unsafe {
+            __dfly_error()
+        }
+    }
+
+    #[cfg(any(target_os = "linux", target_os = "android"))]
+    fn errno_location() -> *mut c_int {
+        extern {
+            fn __errno_location() -> *mut c_int;
+        }
+        unsafe {
+            __errno_location()
+        }
+    }
+
+    *errno_location() = EXPECTED_ERRNO;
+    return -1;
+}
+
+fn main() {
+    let program = c_string!("true");
+    let cwd = c_string!("whatever");
+    let cfg = rtio::ProcessConfig {
+        program: program,
+        args: &[],
+        env: None,
+        cwd: Some(cwd),
+        stdin: rtio::Ignored,
+        stdout: rtio::Ignored,
+        stderr: rtio::Ignored,
+        extra_io: &[],
+        uid: None,
+        gid: None,
+        detach: false
+    };
+
+    match process::Process::spawn(cfg) {
+        Ok(_) => { fail!("spawn() should have failled"); }
+        Err(rtio::IoError { code: err, ..}) => {
+            assert_eq!(err as c_int, EXPECTED_ERRNO);
+        }
+    };
+}