diff --git a/include/labwc.h b/include/labwc.h
index 87f8cfb5..e869f673 100644
--- a/include/labwc.h
+++ b/include/labwc.h
@@ -1,7 +1,6 @@
 #ifndef __LABWC_H
 #define __LABWC_H
 
-#define _POSIX_C_SOURCE 200809L
 #include <getopt.h>
 #include <stdbool.h>
 #include <stdlib.h>
diff --git a/src/action.c b/src/action.c
index 4f933f74..99e1ff77 100644
--- a/src/action.c
+++ b/src/action.c
@@ -1,8 +1,8 @@
 #include <strings.h>
 
-#include "labwc.h"
 #include "common/spawn.h"
 #include "common/log.h"
+#include "labwc.h"
 
 static void reconfigure(void)
 {
diff --git a/src/server.c b/src/server.c
index e65e1896..1ea571d7 100644
--- a/src/server.c
+++ b/src/server.c
@@ -1,3 +1,4 @@
+#define _POSIX_C_SOURCE 200809L
 #include "labwc.h"
 #include "theme/theme.h"
 #include "config/rcxml.h"