diff --git a/src/socket_init.c b/src/socket_init.c
index f20dbdf..a30251f 100644
--- a/src/socket_init.c
+++ b/src/socket_init.c
@@ -20,7 +20,7 @@
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
 
-#define _POSIX_SOURCE 1
+#define _POSIX_C_SOURCE 200112L
 
 #include <stdlib.h>     // for atoi() and exit()
 #include <errno.h>      // for errno