diff --git a/src/charon/network/socket.c b/src/charon/network/socket.c
index fc1559251..97c88be79 100644
--- a/src/charon/network/socket.c
+++ b/src/charon/network/socket.c
@@ -18,6 +18,10 @@
 
 /* for struct in6_pktinfo */
 #define _GNU_SOURCE
+#ifdef __sun
+#define _XPG4_2
+#define __EXTENSIONS__
+#endif
 
 #include <pthread.h>
 #include <sys/types.h>