diff --git a/helpers_fileio.c b/helpers_fileio.c
index 25fd3d0f4..17fa081e8 100644
--- a/helpers_fileio.c
+++ b/helpers_fileio.c
@@ -10,6 +10,7 @@
 #include <stdlib.h>
 #include <string.h>
 #include <errno.h>
+#include <unistd.h>
 
 #ifndef __LIBPAYLOAD__
 #include <fcntl.h>