diff --git a/src/log.c b/src/log.c
index 4cfb01c..0b28570 100644
--- a/src/log.c
+++ b/src/log.c
@@ -12,8 +12,8 @@
  *     https://opensource.org/licenses/BSD-3-Clause
  */
 
-#define _GNU_SOURCE
-#define _POSIX_C_SOURCE 200809L /* strdup */
+#define _GNU_SOURCE /* asprintf, strdup */
+#include <sys/cdefs.h>
 
 #include "log.h"