Index: twisted/python/sendmsg.c
===================================================================
--- twisted/python/sendmsg.c    (revision 34978)
+++ twisted/python/sendmsg.c    (working copy)
@@ -6,6 +6,11 @@
 #define PY_SSIZE_T_CLEAN 1
 #include <Python.h>
 
+#if defined (__SVR4) && defined (__sun)
+# define _XPG4_2 1
+#endif
+
+
 #if PY_VERSION_HEX < 0x02050000 && !defined(PY_SSIZE_T_MIN)
 /* This may cause some warnings, but if you want to get rid of them, upgrade
  * your Python version.  */