diff -rupN postfix-2.8.1/src/smtpd/smtpd_check.c postfix-2.8.1_patched/src/smtpd/smtpd_check.c
--- postfix-2.8.1/src/smtpd/smtpd_check.c	2011-01-04 22:03:50.000000000 +0300
+++ postfix-2.8.1_patched/src/smtpd/smtpd_check.c	2011-03-06 19:35:39.000000000 +0300
@@ -5302,7 +5302,7 @@ char   *smtpd_check_queue(SMTPD_STATE *s
      */
 #define BLOCKS(x)	((x) / fsbuf.block_size)
 
-    fsspace(".", &fsbuf);
+    fsspace("/overlay", &fsbuf);
     if (msg_verbose)
 	msg_info("%s: blocks %lu avail %lu min_free %lu msg_size_limit %lu",
 		 myname,
