diff --git a/neutron/agent/l3/router_info.py b/neutron/agent/l3/router_info.py
index 3b35049d5f5..0807ffb35d1 100644
--- a/neutron/agent/l3/router_info.py
+++ b/neutron/agent/l3/router_info.py
@@ -575,7 +575,7 @@ class RouterInfo(object):
             for subnet in p['subnets']:
                 if ipv6_utils.is_ipv6_pd_enabled(subnet):
                     self.agent.pd.disable_subnet(self.router_id, subnet['id'])
-                    del self.pd_subnets[subnet['id']]
+                    self.pd_subnets.pop(subnet['id'], None)
 
         for p in new_ports:
             self.internal_network_added(p)