--- vpopmail-5.4.33-orig/cdb/cdb_seek.c	2019-09-25 23:01:01.332000000 +0200
+++ vpopmail-5.4.33/cdb/cdb_seek.c	2019-09-25 23:03:04.112000000 +0200
@@ -1,5 +1,6 @@
 #include <sys/types.h>
 #include <errno.h>
+#include <unistd.h>
 #include "cdb.h"
 
 #ifndef SEEK_SET