diff --git a/src/66/66-inservice.c b/src/66/66-inservice.c
index cdf56636874e1ca43925f4145caeb6f16b6a2f28..117a3cd479f7e56f8c9b3b8216fb923a99d89605 100644
--- a/src/66/66-inservice.c
+++ b/src/66/66-inservice.c
@@ -16,6 +16,7 @@
 #include <locale.h>
 #include <langinfo.h>
 #include <sys/types.h>
+#include <sys/unistd.h>
 #include <wchar.h>
 #include <unistd.h>
 //#include <stdio.h>