diff --git a/src/lib/fs.rs b/src/lib/fs.rs
index 09e36ea7945..b15ec23c5b7 100644
--- a/src/lib/fs.rs
+++ b/src/lib/fs.rs
@@ -4,6 +4,7 @@ Module: fs
 File system manipulation
 */
 
+import os;
 import os::getcwd;
 import os_fs;
 
@@ -115,6 +116,28 @@ fn file_is_dir(p: path) -> bool {
     ret str::as_buf(p, {|buf| rustrt::rust_file_is_dir(buf) != 0 });
 }
 
+/*
+Function: make_dir
+
+Creates a directory at the specific path.
+*/
+fn make_dir(p: path, mode: int) -> bool {
+    ret mkdir(p, mode);
+
+    #[cfg(target_os = "win32")]
+    fn mkdir(_p: path, _mode: int) -> bool {
+        // FIXME: turn mode into something useful?
+        let noctx = ptr::null<os::kernel32::LPSECURITY_ATTRIBUTES>();
+        ret str::as_buf(_p, {|buf| os::kernel32::CreateDirectory(buf, noctx) });
+    }
+
+    #[cfg(target_os = "linux")]
+    #[cfg(target_os = "macos")]
+    fn mkdir(_p: path, _mode: int) -> bool {
+        ret str::as_buf(_p, {|buf| os::libc::mkdir(buf, _mode) == 0 });
+    }
+}
+
 /*
 Function: list_dir
 
diff --git a/src/lib/linux_os.rs b/src/lib/linux_os.rs
index 61acc6a4899..093fe542ca9 100644
--- a/src/lib/linux_os.rs
+++ b/src/lib/linux_os.rs
@@ -51,6 +51,7 @@ native mod libc {
     fn pipe(buf: *mutable fd_t) -> c_int;
     fn waitpid(pid: pid_t, &status: c_int, options: c_int) -> pid_t;
     fn readlink(path: str::sbuf, buf: str::sbuf, bufsize: size_t) -> ssize_t;
+    fn mkdir(path: str::sbuf, mode: int) -> int;
 }
 
 mod libc_constants {
diff --git a/src/lib/macos_os.rs b/src/lib/macos_os.rs
index dbea5bcb7fe..e2209f15d2e 100644
--- a/src/lib/macos_os.rs
+++ b/src/lib/macos_os.rs
@@ -40,10 +40,11 @@ native mod libc {
     type dirent;
     fn readdir(d: dir) -> dirent;
     fn getenv(n: str::sbuf) -> str::sbuf;
-    fn setenv(n: str::sbuf, v: str::sbuf, overwrite: c_int) -> c_int;
-    fn unsetenv(n: str::sbuf) -> c_int;
-    fn pipe(buf: *mutable fd_t) -> c_int;
-    fn waitpid(pid: pid_t, &status: c_int, options: c_int) -> pid_t;
+    fn setenv(n: str::sbuf, v: str::sbuf, overwrite: int) -> int;
+    fn unsetenv(n: str::sbuf) -> int;
+    fn pipe(buf: *mutable int) -> int;
+    fn waitpid(pid: int, &status: int, options: int) -> int;
+    fn mkdir(s: str::sbuf, mode: int) -> int;
 }
 
 mod libc_constants {
diff --git a/src/lib/rand.rs b/src/lib/rand.rs
index 37074a6a609..0f8117e901a 100644
--- a/src/lib/rand.rs
+++ b/src/lib/rand.rs
@@ -32,6 +32,13 @@ type rng = obj {
     Return the next random float
     */
     fn next_float() -> float;
+
+    /*
+    Method: gen_str
+
+    Return a random string composed of A-Z, a-z, 0-9.
+    */
+    fn gen_str(len: uint) -> str;
 };
 
 resource rand_res(c: rustrt::rctx) { rustrt::rand_free(c); }
@@ -53,6 +60,19 @@ fn mk_rng() -> rng {
           let scale = u32::max_value as float;
           ret ((u1 / scale + u2) / scale + u3) / scale;
         }
+        fn gen_str(len: uint) -> str {
+            let charset = "ABCDEFGHIJKLMNOPQRSTUVWXYZ" +
+                          "abcdefghijklmnopqrstuvwxyz" +
+                          "0123456789";
+            let s = "";
+            let i = 0u;
+            while (i < len) {
+                let n = rustrt::rand_next(**c) as uint % str::char_len(charset);
+                s = s + str::from_char(str::char_at(charset, n));
+                i += 1u;
+            }
+            s
+        }
     }
     ret rt_rng(@rand_res(rustrt::rand_new()));
 }
diff --git a/src/lib/std.rc b/src/lib/std.rc
index 87184d5e905..ac15964c6fa 100644
--- a/src/lib/std.rc
+++ b/src/lib/std.rc
@@ -13,7 +13,7 @@ export ctypes, either, option, result, four, tri, util;
 export bitv, deque, fun_treemap, list, map, smallintmap, sort, treemap, ufind;
 export rope;
 export ebml, dbg, getopts, json, math, rand, sha1, term, time, unsafe;
-export extfmt, test;
+export extfmt, test, tempfile;
 // FIXME: generic_os and os_fs shouldn't be exported
 export generic_os, os, os_fs;
 
@@ -79,6 +79,7 @@ mod json;
 mod math;
 mod rand;
 mod sha1;
+mod tempfile;
 mod term;
 mod time;
 mod unsafe;
diff --git a/src/lib/tempfile.rs b/src/lib/tempfile.rs
new file mode 100644
index 00000000000..1d29169ecc4
--- /dev/null
+++ b/src/lib/tempfile.rs
@@ -0,0 +1,23 @@
+/*
+Module: tempfile
+
+Temporary files and directories
+*/
+
+import fs;
+import option;
+import option::{none, some};
+import rand;
+
+fn mkdtemp(prefix: str, suffix: str) -> option::t<str> {
+    let r = rand::mk_rng();
+    let i = 0u;
+    while (i < 1000u) {
+        let s = prefix + r.gen_str(16u) + suffix;
+        if fs::make_dir(s, 0x1c0) {  // FIXME: u+rwx
+            ret some(s);
+        }
+        i += 1u;
+    }
+    ret none;
+}
diff --git a/src/lib/win32_os.rs b/src/lib/win32_os.rs
index d85f8995d99..6befe626817 100644
--- a/src/lib/win32_os.rs
+++ b/src/lib/win32_os.rs
@@ -41,15 +41,19 @@ mod libc_constants {
 type DWORD = u32;
 type HMODULE = uint;
 type LPTSTR = str::sbuf;
+type LPCTSTR = str::sbuf;
 
 #[abi = "stdcall"]
 native mod kernel32 {
+    type LPSECURITY_ATTRIBUTES;
     fn GetEnvironmentVariableA(n: str::sbuf, v: str::sbuf, nsize: uint) ->
        uint;
     fn SetEnvironmentVariableA(n: str::sbuf, v: str::sbuf) -> int;
     fn GetModuleFileNameA(hModule: HMODULE,
                           lpFilename: LPTSTR,
                           nSize: DWORD) -> DWORD;
+    fn CreateDirectory(lpPathName: LPCTSTR,
+                       lpSecurityAttributes: LPSECURITY_ATTRIBUTES) -> bool;
 }
 
 // FIXME turn into constants