diff --git a/lib/backend.py b/lib/backend.py
index 820538108abf3c8d1af9ba14ff9f975ba7aa9f2b..4deaaad5daf7e7297aebd0e68270b34d555d341f 100644
--- a/lib/backend.py
+++ b/lib/backend.py
@@ -265,9 +265,7 @@ def ActivateMasterIp():
       err_msg = "Someone else has the master ip, not activating"
       logging.error(err_msg)
   else:
-    ipcls = netutils.IP4Address
-    if family == netutils.IP6Address.family:
-      ipcls = netutils.IP6Address
+    ipcls = netutils.IPAddress.GetClassFromIpFamily(family)
 
     result = utils.RunCmd([constants.IP_COMMAND_PATH, "address", "add",
                            "%s/%s" % (master_ip, master_netmask),