diff --git a/scd/app.c b/scd/app.c
index aac6e0e9b..625f9b914 100644
--- a/scd/app.c
+++ b/scd/app.c
@@ -22,6 +22,7 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#include <unistd.h>
 #include <npth.h>
 
 #include "scdaemon.h"