--- warp.cabal.intermediate	2015-08-26 21:49:57 UTC
+++ warp.cabal
@@ -91,7 +91,7 @@ Library
 
   if flag(warp-debug)
       Cpp-Options:   -DWARP_DEBUG
-  if (os(linux) || os(freebsd) || os(darwin)) && flag(allow-sendfilefd)
+  if (os(linux) || os(freebsd) || os(dragonfly)) && flag(allow-sendfilefd)
       Cpp-Options:   -DSENDFILEFD
       Build-Depends: hashable
       Other-modules: Network.Wai.Handler.Warp.MultiMap