diff --git a/package/network/ipv6/map/Makefile b/package/network/ipv6/map/Makefile
index 382fe0a8ba0bc4b5c5154517a937b6cc7103cad3..2848fe9ea28ac153044c145368922c0c6e5e3cfd 100644
--- a/package/network/ipv6/map/Makefile
+++ b/package/network/ipv6/map/Makefile
@@ -1,5 +1,5 @@
 #
-# Copyright (C) 2014 OpenWrt.org
+# Copyright (C) 2014-2015 OpenWrt.org
 #
 # This is free software, licensed under the GNU General Public License v2.
 # See /LICENSE for more information.
@@ -8,7 +8,7 @@
 include $(TOPDIR)/rules.mk
 
 PKG_NAME:=map
-PKG_VERSION:=2
+PKG_VERSION:=3
 PKG_RELEASE:=1
 PKG_LICENSE:=GPL-2.0
 
diff --git a/package/network/ipv6/map/src/mapcalc.c b/package/network/ipv6/map/src/mapcalc.c
index afce6d24d7007059fea8735d81a755fdc2457c82..b4b3d736f006730c2fe56315c0d637e4cc42accf 100644
--- a/package/network/ipv6/map/src/mapcalc.c
+++ b/package/network/ipv6/map/src/mapcalc.c
@@ -2,7 +2,7 @@
  * mapcalc - MAP parameter calculation
  *
  * Author: Steven Barth <cyrus@openwrt.org>
- * Copyright (c) 2014 cisco Systems, Inc.
+ * Copyright (c) 2014-2015 cisco Systems, Inc.
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 2
@@ -271,8 +271,10 @@ int main(int argc, char *argv[])
 		if (ealen < 0 && pdlen >= 0)
 			ealen = pdlen - prefix6len;
 
-		if (psidlen < 0)
+		if (psidlen <= 0) {
 			psidlen = ealen - (32 - prefix4len);
+			psid = -1;
+		}
 
 		if (psid < 0 && psidlen <= 16 && psidlen >= 0 && pdlen >= 0 && ealen >= psidlen) {
 			bmemcpys64(&psid16, &pd, prefix6len + ealen - psidlen, psidlen);