diff --git a/swaynag/config.c b/swaynag/config.c
index e5e940c7f..40f3f65e8 100644
--- a/swaynag/config.c
+++ b/swaynag/config.c
@@ -3,6 +3,7 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <wordexp.h>
+#include <unistd.h>
 #include "log.h"
 #include "list.h"
 #include "swaynag/swaynag.h"