diff --git a/openstackclient/network/v2/subnet.py b/openstackclient/network/v2/subnet.py
index 10e5859a5f..45e68235b2 100644
--- a/openstackclient/network/v2/subnet.py
+++ b/openstackclient/network/v2/subnet.py
@@ -366,6 +366,12 @@ class SetSubnet(command.Command):
         if not attrs:
             msg = "Nothing specified to be set"
             raise exceptions.CommandError(msg)
+        if 'dns_nameservers' in attrs:
+            attrs['dns_nameservers'] += obj.dns_nameservers
+        if 'host_routes' in attrs:
+            attrs['host_routes'] += obj.host_routes
+        if 'allocation_pools' in attrs:
+            attrs['allocation_pools'] += obj.allocation_pools
         client.update_subnet(obj, **attrs)
         return
 
diff --git a/openstackclient/tests/network/v2/test_subnet.py b/openstackclient/tests/network/v2/test_subnet.py
index 2535bbe6d8..ede3741615 100644
--- a/openstackclient/tests/network/v2/test_subnet.py
+++ b/openstackclient/tests/network/v2/test_subnet.py
@@ -536,6 +536,26 @@ class TestSetSubnet(TestSubnet):
         self.assertRaises(exceptions.CommandError, self.cmd.take_action,
                           parsed_args)
 
+    def test_append_options(self):
+        _testsubnet = network_fakes.FakeSubnet.create_one_subnet(
+            {'dns_nameservers': ["10.0.0.1"]})
+        self.network.find_subnet = mock.Mock(return_value=_testsubnet)
+        arglist = [
+            '--dns-nameserver', '10.0.0.2',
+            _testsubnet.name,
+        ]
+        verifylist = [
+            ('dns_nameservers', ['10.0.0.2']),
+        ]
+        parsed_args = self.check_parser(self.cmd, arglist, verifylist)
+        result = self.cmd.take_action(parsed_args)
+        attrs = {
+            'dns_nameservers': ['10.0.0.2', '10.0.0.1'],
+        }
+        self.network.update_subnet.assert_called_once_with(
+            _testsubnet, **attrs)
+        self.assertIsNone(result)
+
 
 class TestShowSubnet(TestSubnet):
     # The subnets to be shown