diff --git a/wmstatus.c b/wmstatus.c
index 4c91bba..6277c04 100644
--- a/wmstatus.c
+++ b/wmstatus.c
@@ -22,6 +22,7 @@
 
 // openat, dirfd
 #define _XOPEN_SOURCE 700
+#define _ATFILE_SOURCE
 #define _GNU_SOURCE
 
 #include "config.h"