Index: checkpassword-0.90/checkpassword.c
===================================================================
--- checkpassword-0.90.orig/checkpassword.c
+++ checkpassword-0.90/checkpassword.c
@@ -1,3 +1,5 @@
+#include <unistd.h>
+
 #include "error.h"
 #include "pathexec.h"
 #include "prot.h"