diff --git a/liblash/socket.c b/liblash/socket.c
index b6e1b25..91caf0f 100644
--- a/liblash/socket.c
+++ b/liblash/socket.c
@@ -20,6 +20,11 @@
 
 #define _POSIX_SOURCE /* addrinfo */
 
+#ifdef LASH_BUILD
+#define _GNU_SOURCE
+#include "config.h"
+#endif /* LASH_BUILD */
+
 #include <stdint.h>
 #include <sys/types.h>
 #include <sys/socket.h>