diff --git a/neutron/db/db_base_plugin_v2.py b/neutron/db/db_base_plugin_v2.py
index 87ba2531577..d3d7659437f 100644
--- a/neutron/db/db_base_plugin_v2.py
+++ b/neutron/db/db_base_plugin_v2.py
@@ -705,13 +705,12 @@ class NeutronDbPluginV2(db_base_plugin_common.DbBasePluginCommon,
             s['allocation_pools'] = range_pools
 
         # If either gateway_ip or allocation_pools were specified
-        new_gateway_ip = s.get('gateway_ip')
-        gateway_ip_changed = (new_gateway_ip and
-                              new_gateway_ip != db_subnet.gateway_ip)
+        gateway_ip = s.get('gateway_ip', db_subnet.gateway_ip)
+        gateway_ip_changed = gateway_ip != db_subnet.gateway_ip
         if gateway_ip_changed or s.get('allocation_pools') is not None:
-            gateway_ip = new_gateway_ip or db_subnet.gateway_ip
             pools = range_pools if range_pools is not None else db_pools
-            self.ipam.validate_gw_out_of_pools(gateway_ip, pools)
+            if gateway_ip:
+                self.ipam.validate_gw_out_of_pools(gateway_ip, pools)
 
         if gateway_ip_changed:
             # Provide pre-update notification not to break plugins that don't
diff --git a/neutron/tests/unit/db/test_db_base_plugin_v2.py b/neutron/tests/unit/db/test_db_base_plugin_v2.py
index 19be2beb3d1..abf8f0dfe39 100644
--- a/neutron/tests/unit/db/test_db_base_plugin_v2.py
+++ b/neutron/tests/unit/db/test_db_base_plugin_v2.py
@@ -4653,6 +4653,37 @@ class TestSubnetsV2(NeutronDbPluginV2TestCase):
             self.assertEqual(data['subnet']['host_routes'],
                              res['subnet']['host_routes'])
 
+    def _test_update_subnet(self, old_gw=None, new_gw=None,
+                            check_gateway=False):
+        allocation_pools = [{'start': '192.168.0.16', 'end': '192.168.0.254'}]
+        with self.network() as network:
+            with self.subnet(network=network,
+                             gateway_ip=old_gw,
+                             allocation_pools=allocation_pools,
+                             cidr='192.168.0.0/24') as subnet:
+                data = {
+                    'subnet': {
+                        'allocation_pools': [
+                            {'start': '192.168.0.10', 'end': '192.168.0.20'},
+                            {'start': '192.168.0.30', 'end': '192.168.0.40'}],
+                        'gateway_ip': new_gw}}
+                req = self.new_update_request('subnets', data,
+                                              subnet['subnet']['id'])
+                res = req.get_response(self.api)
+                self.assertEqual(200, res.status_code)
+                self._verify_updated_subnet_allocation_pools(
+                    res, with_gateway_ip=check_gateway)
+
+    def test_update_subnet_from_no_gw_to_no_gw(self):
+        self._test_update_subnet()
+
+    def test_update_subnet_from_gw_to_no_gw(self):
+        self._test_update_subnet(old_gw='192.168.0.15')
+
+    def test_update_subnet_from_gw_to_new_gw(self):
+        self._test_update_subnet(old_gw='192.168.0.15',
+                                 new_gw='192.168.0.9', check_gateway=True)
+
     def test_update_subnet_route_with_too_many_entries(self):
         with self.subnet() as subnet:
             data = {'subnet': {'host_routes': [
diff --git a/neutron/tests/unit/plugins/opencontrail/test_contrail_plugin.py b/neutron/tests/unit/plugins/opencontrail/test_contrail_plugin.py
index 55b2abc2710..11b265008af 100644
--- a/neutron/tests/unit/plugins/opencontrail/test_contrail_plugin.py
+++ b/neutron/tests/unit/plugins/opencontrail/test_contrail_plugin.py
@@ -221,6 +221,12 @@ class TestContrailSubnetsV2(test_plugin.TestSubnetsV2,
     def test_delete_subnet_dhcp_port_associated_with_other_subnets(self):
         self.skipTest("There is no dhcp port in contrail")
 
+    def test_update_subnet_from_gw_to_no_gw(self):
+        self.skipTest("There is no empty gateway support in contrail")
+
+    def test_update_subnet_from_no_gw_to_no_gw(self):
+        self.skipTest("There is no empty gateway support in contrail")
+
     def _helper_test_validate_subnet(self, option, exception):
         cfg.CONF.set_override(option, 0)
         with self.network() as network: