--- rts/PosixSource.h.orig	2011-07-28 19:12:04 +0200
+++ rts/PosixSource.h	2011-08-02 09:29:37 +0200
@@ -11,7 +11,7 @@
 
 #include <ghcplatform.h>
 
-#if defined(freebsd_HOST_OS)
+#if defined(freebsd_HOST_OS) || defined(dragonfly_HOST_OS)
 #define _POSIX_C_SOURCE 200112L
 #define _XOPEN_SOURCE   600
 #else