diff --git a/assets/china-ip.py b/assets/china-ip.py
index 94f06dc..f964bd2 100755
--- a/assets/china-ip.py
+++ b/assets/china-ip.py
@@ -2,7 +2,9 @@
 # -*- coding: utf-8 -*-
 
 import os
-from IPy import IP, IPSet
+from netaddr import IPSet
+from netaddr import IPAddress
+from netaddr import IPNetwork
 
 operators = ['china', 'cmcc', 'chinanet', 'unicom', 'tietong', 'cernet', 'cstnet', 'drpeng', 'googlecn']
 operators += ['%s6' % x for x in operators]  # add `...6` suffix
@@ -12,20 +14,20 @@ source = [
     'curl -sL https://github.com/17mon/china_ip_list/raw/master/china_ip_list.txt',
 ] + ['curl -sL https://gaoyifan.github.io/china-operator-ip/%s.txt' % x for x in operators]
 
-ipv4 = IPSet()
-ipv6 = IPSet()
 ipAddrs = set()
 for script in source:  # traverse fetch commands
     raw = os.popen(script).read().split('\n')
     ipAddrs.update(filter(None, raw))
-for ipAddr in ipAddrs:
+
+ipv4 = IPSet()
+ipv6 = IPSet()
+for ipAddr in ipAddrs:  # load all IP data
     try:
-        ip = IP(ipAddr)  # ip format check
-        (ipv4 if ip.version() == 4 else ipv6).add(ip)
+        ip = IPNetwork(ipAddr) if '/' in ipAddr else IPAddress(ipAddr)
+        ipv4.add(ip) if ip.version == 4 else ipv6.add(ip)
     except:
         pass
 
-release = [('%s' if '/' in str(ip) else '%s/32') % str(ip) for ip in ipv4]  # format into CIDR
-release += [('%s' if '/' in str(ip) else '%s/128') % str(ip) for ip in ipv6]
-with open('china-ip.txt', 'w') as fileObj:
-    fileObj.write('\n'.join(release) + '\n')
+with open('china-ip.txt', 'w') as fileObj:  # save to file
+    fileObj.write('\n'.join([str(ip) for ip in ipv4.iter_cidrs()]) + '\n')  # format into CIDR
+    fileObj.write('\n'.join([str(ip) for ip in ipv6.iter_cidrs()]) + '\n')