diff --git a/p4app/controller.py b/p4app/controller.py
index 353691e..cb3ac2a 100644
--- a/p4app/controller.py
+++ b/p4app/controller.py
@@ -86,7 +86,7 @@ class L2Controller(object):
 
     def gen_ndp_multicast_addr(self, addr):
         """ append the 24 bit of the address to the multicast address"""
-        return ipaddress.ip_address(int(self.info['ndp_multicast']) + (int(addr) & 0xffffff))
+        return ipaddress.ip_address(int(self.info['ndp_multicast'].network_address) + (int(addr) & 0xffffff))
 
     @staticmethod
     def add_host_ips(host, net, ipaddr, dev):