diff --git a/regress/unpack.c b/regress/unpack.c
index b6924093..802391de 100644
--- a/regress/unpack.c
+++ b/regress/unpack.c
@@ -42,6 +42,7 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#include <unistd.h>
 
 #ifndef MAXPATHLEN
 #define MAXPATHLEN 1024