diff --git a/utils/he_ipv6/tunnelbroker.py b/utils/he_ipv6/tunnelbroker.py
index 7d0c771..716f6b2 100644
--- a/utils/he_ipv6/tunnelbroker.py
+++ b/utils/he_ipv6/tunnelbroker.py
@@ -145,6 +145,16 @@ class TunnelBroker(object):
         for assignment in self.tun.assignments:
             for a in assignment.iface_addrs:
                 # The interface-specific ":1" addrs.
+                # Try to remove first in case it's already assigned.
+                try:
+                    ipr.addr('del',
+                             index = assignment.iface_idx,
+                             address = a.str,
+                             mask = a.prefix,
+                             family = socket.AF_INET6)
+                    logger.debug('Removed {0} with prefix {1} from {2}.'.format(a.str, a.prefixlen, assignment.iface))
+                except Exception as e:
+                    pass
                 try:
                     ipr.addr('add',
                              index = assignment.iface_idx,
@@ -159,13 +169,14 @@ class TunnelBroker(object):
                     raise e
             # The SLAAC prefixes.
             for b in assignment.iface_blocks:
+                # Try to remove first in case it's already assigned.
                 try:
                     ipr.addr('del',
                              index = assignment.iface_idx,
-                             address = b.str,
+                             address = str(b),
                              mask = b.prefixlen,
                              family = socket.AF_INET6)
-                    logger.debug('Removed {0} with prefix {1} from {2}.'.format(b.str, b.prefixlen, assignment.iface))
+                    logger.debug('Removed {0} with prefix {1} from {2}.'.format(str(b), b.prefixlen, assignment.iface))
                 except Exception as e:
                     pass
                 try: