diff --git a/blockcheck.py b/blockcheck.py
index 99178fb..05f5cb6 100755
--- a/blockcheck.py
+++ b/blockcheck.py
@@ -366,8 +366,8 @@ def _mask_ip(ipaddr):
         ipaddr_s = ipaddress.ip_interface(ipaddr + '/24')
         return str(ipaddr_s.network).replace('0/24', 'xxx')
     if ipaddr_s.version == 6:
-        ipaddr_s = ipaddress.ip_interface(ipaddr + '/48')
-        return str(ipaddr_s.network).replace(':/48', 'xxxx::')
+        ipaddr_s = ipaddress.ip_interface(ipaddr + '/64')
+        return str(ipaddr_s.network).replace(':/64', 'xxxx::')
     return None
 
 def _dpi_send(host, port, data, fragment_size=0, fragment_count=0):