diff --git a/keystone/common/validation/__init__.py b/keystone/common/validation/__init__.py
index 8284bac666..0311de5dad 100644
--- a/keystone/common/validation/__init__.py
+++ b/keystone/common/validation/__init__.py
@@ -40,6 +40,14 @@ def nullable(property_schema):
     #                do that yet so I'm not wasting time on it
     new_schema = property_schema.copy()
     new_schema['type'] = [property_schema['type'], 'null']
+    # NOTE(kmalloc): If enum is specified (such as our boolean case) ensure we
+    # add null to the enum as well so that null can be passed/validated as
+    # expected. Without adding to the enum, null will not validate as enum is
+    # explicitly listing valid values. According to the JSON Schema
+    # specification, the values must be unique in the enum array.
+    if 'enum' in new_schema and None not in new_schema['enum']:
+        # In the enum the 'null' is NoneType
+        new_schema['enum'].append(None)
     return new_schema
 
 
diff --git a/keystone/tests/unit/test_validation.py b/keystone/tests/unit/test_validation.py
index a40bf527f9..485c0ba1c2 100644
--- a/keystone/tests/unit/test_validation.py
+++ b/keystone/tests/unit/test_validation.py
@@ -11,6 +11,7 @@
 # License for the specific language governing permissions and limitations
 # under the License.
 
+import copy
 import uuid
 
 from keystone.application_credential import schema as app_cred_schema
@@ -109,6 +110,43 @@ _INVALID_FILTERS = ['some string', 1, 0, True, False]
 _INVALID_NAMES = [True, 24, ' ', '']
 
 
+class CommonValidationTestCase(unit.BaseTestCase):
+
+    def test_nullable_type_only(self):
+        bool_without_enum = copy.deepcopy(parameter_types.boolean)
+        bool_without_enum.pop('enum')
+        schema_type_only = {
+            'type': 'object',
+            'properties': {'test': validation.nullable(bool_without_enum)},
+            'additionalProperties': False,
+            'required': ['test']}
+
+        # Null should be in the types
+        self.assertIn('null', schema_type_only['properties']['test']['type'])
+        # No Enum, and nullable should not have added it.
+        self.assertNotIn('enum', schema_type_only['properties']['test'].keys())
+        validator = validators.SchemaValidator(schema_type_only)
+        reqs_to_validate = [{'test': val} for val in [True, False, None]]
+        for req in reqs_to_validate:
+            validator.validate(req)
+
+    def test_nullable_with_enum(self):
+        schema_with_enum = {
+            'type': 'object',
+            'properties': {
+                'test': validation.nullable(parameter_types.boolean)},
+            'additionalProperties': False,
+            'required': ['test']}
+
+        # Null should be in enum and type
+        self.assertIn('null', schema_with_enum['properties']['test']['type'])
+        self.assertIn(None, schema_with_enum['properties']['test']['enum'])
+        validator = validators.SchemaValidator(schema_with_enum)
+        reqs_to_validate = [{'test': val} for val in [True, False, None]]
+        for req in reqs_to_validate:
+            validator.validate(req)
+
+
 class EntityValidationTestCase(unit.BaseTestCase):
 
     def setUp(self):
@@ -1945,9 +1983,7 @@ class UserValidationTestCase(unit.BaseTestCase):
                 ro.IGNORE_CHANGE_PASSWORD_OPT.option_name: None
             }
         }
-        self.assertRaises(exception.SchemaValidationError,
-                          self.create_user_validator.validate,
-                          request_to_validate)
+        self.create_user_validator.validate(request_to_validate)
 
     def test_user_update_with_options_change_password_required(self):
         request_to_validate = {
diff --git a/releasenotes/notes/bug-1763824-3d2f5169af9d42f.yaml b/releasenotes/notes/bug-1763824-3d2f5169af9d42f.yaml
new file mode 100644
index 0000000000..7fb8be5cfd
--- /dev/null
+++ b/releasenotes/notes/bug-1763824-3d2f5169af9d42f.yaml
@@ -0,0 +1,6 @@
+---
+fixes:
+  - |
+    [`bug 1763824 <https://bugs.launchpad.net/keystone/+bug/1763824>`_]
+    JSON Schema implementation ``nullable`` in keystone.common.validation now
+    properly adds ``None`` to the enum if the enum exists.