diff --git a/posix-paths.cabal b/posix-paths.cabal
--- a/posix-paths.cabal
+++ b/posix-paths.cabal
@@ -1,5 +1,5 @@
 name:		posix-paths
-version:  0.2.0.3
+version:  0.2.0.4
 license:	BSD3
 license-file:	LICENSE
 maintainer:	jwlato@gmail.com
diff --git a/src/System/Posix/Directory/Foreign.hsc b/src/System/Posix/Directory/Foreign.hsc
--- a/src/System/Posix/Directory/Foreign.hsc
+++ b/src/System/Posix/Directory/Foreign.hsc
@@ -12,11 +12,39 @@
 #include <fcntl.h>
 
 newtype DirType = DirType Int deriving (Eq, Show)
-newtype Flags = Flags { unFlags :: Int } deriving (Eq, Show)
+data Flags = Flags Int | UnsupportedFlag String deriving (Eq, Show)
 
+unFlags :: Flags -> Int
+unFlags (Flags i) = i
+unFlags (UnsupportedFlag name) = error (name ++ " is not supported on this platform")
+
+-- |Returns @True@ if posix-paths was compiled with support for the provided
+-- flag. (As of this writing, the only flag for which this check may be
+-- necessary is 'oCloexec'; all other flags will always yield @True@.)
+isSupported :: Flags -> Bool
+isSupported (Flags _) = True
+isSupported _ = False
+
+-- |@O_CLOEXEC@ is not supported on every POSIX platform. Use
+-- @'isSupported' oCloexec@ to determine if support for @O_CLOEXEC@ was
+-- compiled into your version of posix-paths. (If not, using @oCloexec@ will
+-- throw an exception.)
+oCloexec :: Flags
+#ifdef O_CLOEXEC
+oCloexec = Flags #{const O_CLOEXEC}
+#else
+{-# WARNING oCloexec
+    "This version of posix-paths was compiled without @O_CLOEXEC@ support." #-}
+oCloexec = UnsupportedFlag "O_CLOEXEC"
+#endif
+
+-- If these enum declarations occur earlier in the file, haddock
+-- gets royally confused about the above doc comments.
+-- Probably http://trac.haskell.org/haddock/ticket/138
+
 #{enum DirType, DirType, DT_BLK, DT_CHR, DT_DIR, DT_FIFO, DT_LNK, DT_REG, DT_SOCK, DT_UNKNOWN}
 
-#{enum Flags, Flags, O_APPEND, O_ASYNC, O_CLOEXEC, O_CREAT, O_DIRECTORY, O_EXCL, O_NOCTTY, O_NOFOLLOW, O_NONBLOCK, O_RDONLY, O_SYNC, O_TRUNC}
+#{enum Flags, Flags, O_APPEND, O_ASYNC, O_CREAT, O_DIRECTORY, O_EXCL, O_NOCTTY, O_NOFOLLOW, O_NONBLOCK, O_RDONLY, O_SYNC, O_TRUNC}
 
 pathMax :: Int
 pathMax = #{const PATH_MAX}