diff --git a/neutron/extensions/subnet_service_types.py b/neutron/extensions/subnet_service_types.py
index 23611463d42..94000767c45 100644
--- a/neutron/extensions/subnet_service_types.py
+++ b/neutron/extensions/subnet_service_types.py
@@ -14,6 +14,7 @@ from neutron_lib.api import extensions
 from neutron_lib.api import validators
 from neutron_lib import constants
 from neutron_lib import exceptions
+import six
 import webob.exc
 
 from neutron._i18n import _
@@ -29,6 +30,10 @@ class InvalidSubnetServiceType(exceptions.InvalidInput):
                 "to a valid device owner.")
 
 
+class InvalidInputSubnetServiceType(exceptions.InvalidInput):
+    message = _("Subnet service type %(service_type)s is not a string.")
+
+
 def _validate_subnet_service_types(service_types, valid_values=None):
     if service_types:
         if not isinstance(service_types, list):
@@ -41,7 +46,9 @@ def _validate_subnet_service_types(service_types, valid_values=None):
         prefixes += constants.DEVICE_OWNER_COMPUTE_PREFIX
 
         for service_type in service_types:
-            if not service_type.startswith(tuple(prefixes)):
+            if not isinstance(service_type, six.text_type):
+                raise InvalidInputSubnetServiceType(service_type=service_type)
+            elif not service_type.startswith(tuple(prefixes)):
                 raise InvalidSubnetServiceType(service_type=service_type)
 
 
diff --git a/neutron/tests/unit/extensions/test_subnet_service_types.py b/neutron/tests/unit/extensions/test_subnet_service_types.py
index 030ec3c0203..bd0d7d60084 100644
--- a/neutron/tests/unit/extensions/test_subnet_service_types.py
+++ b/neutron/tests/unit/extensions/test_subnet_service_types.py
@@ -98,6 +98,7 @@ class SubnetServiceTypesExtensionTestCase(
 
     def test_create_subnet_invalid_type(self):
         self._test_create_subnet(['foo'], expect_fail=True)
+        self._test_create_subnet([1], expect_fail=True)
 
     def test_create_subnet_no_type(self):
         res = self._create_service_subnet()
@@ -105,12 +106,12 @@ class SubnetServiceTypesExtensionTestCase(
         subnet = subnet['subnet']
         self.assertFalse(subnet['service_types'])
 
-    def _test_update_subnet(self, subnet, service_types, expect_fail=False):
+    def _test_update_subnet(self, subnet, service_types, fail_code=None):
         data = {'subnet': {'service_types': service_types}}
         req = self.new_update_request('subnets', data, subnet['id'])
         res = self.deserialize(self.fmt, req.get_response(self.api))
-        if expect_fail:
-            self.assertEqual('InvalidSubnetServiceType',
+        if fail_code is not None:
+            self.assertEqual(fail_code,
                              res['NeutronError']['type'])
         else:
             subnet = res['subnet']
@@ -155,12 +156,14 @@ class SubnetServiceTypesExtensionTestCase(
         self._test_update_subnet(subnet, service_types)
 
     def test_update_subnet_invalid_type(self):
-        service_types = ['foo']
         # Create a subnet with no service type
         res = self._create_service_subnet()
         subnet = self.deserialize('json', res)['subnet']
-        # Update it with an invalid service type
-        self._test_update_subnet(subnet, service_types, expect_fail=True)
+        # Update it with invalid service type(s)
+        self._test_update_subnet(subnet, ['foo'],
+                                 fail_code='InvalidSubnetServiceType')
+        self._test_update_subnet(subnet, [2],
+                                 fail_code='InvalidInputSubnetServiceType')
 
     def _assert_port_res(self, port, service_type, subnet, fallback,
                          error='IpAddressGenerationFailureNoMatchingSubnet'):