diff --git a/src/libstd/sys/unix/os.rs b/src/libstd/sys/unix/os.rs
index 3c53db53f85..5bc5567df2f 100644
--- a/src/libstd/sys/unix/os.rs
+++ b/src/libstd/sys/unix/os.rs
@@ -386,24 +386,33 @@ pub fn env() -> Env {
     let _g = ENV_LOCK.lock();
     return unsafe {
         let mut environ = *environ();
-        if environ as usize == 0 {
+        if environ == ptr::null() {
             panic!("os::env() failure getting env string from OS: {}",
                    io::Error::last_os_error());
         }
         let mut result = Vec::new();
         while *environ != ptr::null() {
-            result.push(parse(CStr::from_ptr(*environ).to_bytes()));
+            if let Some(key_value) = parse(CStr::from_ptr(*environ).to_bytes()) {
+                result.push(key_value);
+            }
             environ = environ.offset(1);
         }
         Env { iter: result.into_iter(), _dont_send_or_sync_me: ptr::null_mut() }
     };
 
-    fn parse(input: &[u8]) -> (OsString, OsString) {
-        let mut it = input.splitn(2, |b| *b == b'=');
-        let key = it.next().unwrap().to_vec();
-        let default: &[u8] = &[];
-        let val = it.next().unwrap_or(default).to_vec();
-        (OsStringExt::from_vec(key), OsStringExt::from_vec(val))
+    fn parse(input: &[u8]) -> Option<(OsString, OsString)> {
+        // Strategy (copied from glibc): Variable name and value are separated
+        // by an ASCII equals sign '='. Since a variable name must not be
+        // empty, allow variable names starting with an equals sign. Skip all
+        // malformed lines.
+        if input.is_empty() {
+            return None;
+        }
+        let pos = input[1..].iter().position(|&b| b == b'=').map(|p| p + 1);
+        pos.map(|p| (
+            OsStringExt::from_vec(input[..p].to_vec()),
+            OsStringExt::from_vec(input[p+1..].to_vec()),
+        ))
     }
 }
 
diff --git a/src/test/run-pass/env-funky-keys.rs b/src/test/run-pass/env-funky-keys.rs
new file mode 100644
index 00000000000..3ee20980747
--- /dev/null
+++ b/src/test/run-pass/env-funky-keys.rs
@@ -0,0 +1,45 @@
+// Copyright 2015 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 this test on Android, because it segfaults there.
+
+// ignore-android
+// ignore-windows
+// no-prefer-dynamic
+
+#![feature(convert)]
+#![feature(libc)]
+
+extern crate libc;
+
+use libc::c_char;
+use libc::execve;
+use std::env;
+use std::ffi::OsStr;
+use std::ptr;
+
+fn main() {
+    if env::args_os().next().is_none() {
+        for (key, value) in env::vars_os() {
+            panic!("found env value {:?} {:?}", key, value);
+        }
+        return;
+    }
+
+    let current_exe = env::current_exe().unwrap().into_os_string().to_cstring().unwrap();
+    let new_env_var = OsStr::new("FOOBAR").to_cstring().unwrap();
+    let filename: *const c_char = current_exe.as_ptr();
+    let argv: &[*const c_char] = &[ptr::null()];
+    let envp: &[*const c_char] = &[new_env_var.as_ptr(), ptr::null()];
+    unsafe {
+        execve(filename, &argv[0], &envp[0]);
+    }
+    panic!("execve failed");
+}
diff --git a/src/test/run-pass/env-vars.rs b/src/test/run-pass/env-vars.rs
index d86f63c9cb9..933d9a728db 100644
--- a/src/test/run-pass/env-vars.rs
+++ b/src/test/run-pass/env-vars.rs
@@ -14,10 +14,7 @@ use std::env::*;
 fn main() {
     for (k, v) in vars_os() {
         let v2 = var_os(&k);
-        // MingW seems to set some funky environment variables like
-        // "=C:=C:\MinGW\msys\1.0\bin" and "!::=::\" that are returned
-        // from vars() but not visible from var().
-        assert!(v2.is_none() || v2.as_ref().map(|s| &**s) == Some(&*v),
+        assert!(v2.as_ref().map(|s| &**s) == Some(&*v),
                 "bad vars->var transition: {:?} {:?} {:?}", k, v, v2);
     }
 }